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Employee costs and numbers
12 Months Ended
Dec. 31, 2018
Additional information [abstract]  
Employee costs and numbers
Pensions and other post-retirement benefits
Most group companies have pension plans, the forms and benefits of which vary with conditions and practices in the countries concerned. Pension benefits may be provided through defined contribution plans (money purchase schemes) or defined benefit plans (final salary and other types of schemes with committed pension benefit payments). For defined contribution plans, retirement benefits are determined by the value of funds arising from contributions paid in respect of each employee. For defined benefit plans, retirement benefits are based on such factors as an employee’s pensionable salary and length of service. Defined benefit plans may be funded or unfunded. The assets of funded plans are generally held in separately administered trusts.
For information on significant estimates and judgements made in relation to accounting for these plans see Pensions and other post-retirement benefits in Note 1.
The primary pension arrangement in the UK is a funded final salary pension plan under which retired employees draw the majority of their benefit as an annuity. This pension plan is governed by a corporate trustee whose board is composed of four member-nominated directors, four company-nominated directors, an independent director and an independent chairman nominated by the company. The trustee board is required by law to act in the best interests of the plan participants and is responsible for setting certain policies, such as investment policies of the plan. The UK plan is closed to new joiners but remains open to ongoing accrual for current members. New joiners in the UK are eligible for membership of a defined contribution plan.
24. Pensions and other post-retirement benefits – continued
In the US, all pension benefits now accrue under a cash balance formula. Benefits previously accrued under final salary formulas are legally protected. Retiring US employees typically take their pension benefit in the form of a lump sum payment upon retirement. The plan is funded and its assets are overseen by a fiduciary Investment Committee composed of six BP employees appointed by the president of BP Corporation North America Inc. (the appointing officer). The Investment Committee is required by law to act in the best interests of the plan participants and is responsible for setting certain policies, such as the investment policies of the plan. US employees are also eligible to participate in a defined contribution (401k) plan in which employee contributions are matched with company contributions. In the US, group companies also provide post-retirement healthcare to retired employees and their dependants (and, in certain cases, life insurance coverage); the entitlement to these benefits is usually based on the employee remaining in service until a specified age and completion of a minimum period of service.
In the Eurozone, there are defined benefit pension plans in Germany, France, the Netherlands and other countries. In Germany and France, the majority of the pensions are unfunded, in line with market practice. In Germany, the group’s largest Eurozone plan, employees receive a pension and also have a choice to supplement their core pension through salary sacrifice. For employees who joined since 2002 the core pension benefit is a career average plan with retirement benefits based on such factors as an employee’s pensionable salary and length of service. The returns on the notional contributions made by both the company and employees are based on the interest rate which is set out in German tax law. Retired German employees take their pension benefit typically in the form of an annuity. The German plans are governed by legal agreements between BP and the works council or between BP and the trade union.
The level of contributions to funded defined benefit plans is the amount needed to provide adequate funds to meet pension obligations as they fall due. During 2018 the aggregate level of contributions was $610 million (2017 $637 million and 2016 $651 million). The aggregate level of contributions in 2019 is expected to be approximately $700 million, and includes contributions in all countries that we expect to be required to make contributions by law or under contractual agreements, as well as an allowance for discretionary funding.
For the primary UK plan there is a funding agreement between the group and the trustee. On an annual basis the latest funding position is reviewed and a schedule of contributions is agreed covering the next five years. Contractually committed funding amounted to $1,275 million at 31 December 2018, all of which relates to future service. This amount is included in the group’s committed cash flows relating to pensions and other post-retirement benefit plans as set out in the table of contractual obligations on page 278.
The surplus relating to the primary UK pension plan is recognized on the balance sheet on the basis that the company is entitled to a refund of any remaining assets once all members have left the plan.
Pension contributions in the US are determined by legislation and are supplemented by discretionary contributions. No contributions were made into the primary US pension plan in 2018 and no statutory funding requirement is expected in the next 12 months.
The surplus relating to the primary US fund is recognized on the balance sheet on the basis that economic benefit can be gained from the surplus through a reduction in future contributions.
There was no minimum funding requirement for the US plan, and no significant minimum funding requirements in other countries at 31 December 2018.
The obligation and cost of providing pensions and other post-retirement benefits is assessed annually using the projected unit credit method. The date of the most recent actuarial review was 31 December 2018. The UK plans are subject to a formal actuarial valuation every three years; valuations are required more frequently in many other countries. The most recent formal actuarial valuation of the UK pension plans was as at 31 December 2017. A valuation of the US plan and largest Eurozone plans are carried out annually.
The material financial assumptions used to estimate the benefit obligations of the various plans are set out below. The assumptions are reviewed by management at the end of each year, and are used to evaluate the accrued benefit obligation at 31 December and pension expense for the following year.
 
 
 
 
 
 
 
 
 
 
%
Financial assumptions used to determine benefit obligation
 
 
 
UK
 
 
US
 
 
Eurozone
 
2018
2017
2016
2018
2017
2016
2018
2017
2016
Discount rate for plan liabilities
 
2.9
2.5
2.7
4.1
3.5
3.9
2.0
1.9
1.7
Rate of increase in salaries
 
3.8
4.1
4.6
3.9
4.1
4.2
3.1
3.0
3.0
Rate of increase for pensions in payment
 
3.0
2.9
3.0
1.5
1.4
1.5
Rate of increase in deferred pensions
 
3.0
2.9
3.0
0.5
0.6
0.5
Inflation for plan liabilities
 
3.1
3.1
3.2
1.5
1.7
1.8
1.7
1.6
1.6
 
 
 
 
 
 
 
 
 
 
%
Financial assumptions used to determine benefit expense
 
 
 
UK
 
 
US
 
 
Eurozone
 
2018
2017
2016
2018
2017
2016
2018
2017
2016
Discount rate for plan service cost
 
2.6
2.7
4.0
3.6
4.1
4.2
2.4
2.1
2.7
Discount rate for plan other finance expense
 
2.5
2.7
3.9
3.5
3.9
4.0
1.9
1.7
2.4
Inflation for plan service cost
 
3.1
3.2
3.1
1.7
1.8
1.5
1.6
1.6
1.8

The discount rate assumptions are based on third-party AA corporate bond indices and for our largest plans in the UK, US and the Eurozone we use yields that reflect the maturity profile of the expected benefit payments. The inflation rate assumptions for our UK and US plans are based on the difference between the yields on index-linked and fixed-interest long-term government bonds. In other countries, including the Eurozone, we use this approach, or advice from the local actuary depending on the information available. The inflation assumptions are used to determine the rate of increase for pensions in payment and the rate of increase in deferred pensions where there is such an increase.
The assumptions for the rate of increase in salaries are based on the inflation assumption plus an allowance for expected long-term real salary growth. These include an allowance for promotion-related salary growth, of up to 0.8% depending on country.
24. Pensions and other post-retirement benefits – continued
In addition to the financial assumptions, we regularly review the demographic and mortality assumptions. The mortality assumptions reflect best practice in the countries in which we provide pensions, and have been chosen with regard to applicable published tables adjusted where appropriate to reflect the experience of the group and an extrapolation of past longevity improvements into the future. BP’s most substantial pension liabilities are in the UK, the US and the Eurozone where our mortality assumptions are as follows:
 
 
 
 
 
 
 
 
 
 
Years

Mortality assumptions
 
 
 
UK

 
 
US

 
 
Eurozone

 
 
2018

2017

2016

2018

2017

2016

2018

2017

2016

Life expectancy at age 60 for a male currently aged 60
 
27.4

27.4

28.0

25.1

25.1

25.7

25.6

25.1

25.0

Life expectancy at age 60 for a male currently aged 40
 
28.9

29.0

30.0

26.9

26.8

27.5

28.1

27.6

27.6

Life expectancy at age 60 for a female currently aged 60
 
28.8

28.8

29.5

28.5

28.4

29.3

29.0

29.0

28.9

Life expectancy at age 60 for a female currently aged 40
 
30.6

30.5

31.9

30.1

30.0

31.0

31.2

31.4

31.3


Pension plan assets are generally held in trusts, the primary objective of which is to accumulate assets sufficient to meet the obligations of the plans. The assets of the trusts are invested in a manner consistent with fiduciary obligations and principles that reflect current practices in portfolio management.
A significant proportion of the assets are held in equities, which are expected to generate a higher level of return over the long term, with an acceptable level of risk. In order to provide reasonable assurance that no single security or type of security has an unwarranted impact on the total portfolio, the investment portfolios are highly diversified.
The trustee’s long-term investment objective for the primary UK plan as it matures is to invest in assets whose value changes in the same way as the plan liabilities, in order to reduce the level of funding risk. To move towards this objective, the UK plan uses a liability driven investment (LDI) approach for part of the portfolio, investing primarily in government bonds to achieve this matching effect for the most significant plan liability assumptions of interest rate and inflation rate. This is partly funded by short-term sale and repurchase agreements, whereby the plan borrows money using existing bonds as security and which will be bought back at a specified price at an agreed future date. The funds raised are used to invest in further bonds to increase the proportion of assets which match the plan liabilities. The borrowings are shown separately in the analysis of pension plan assets in the table below.
For the primary UK pension plan there is an agreement with the trustee to increase the proportion of assets with liability matching characteristics over time primarily by reducing the proportion of plan assets held as equities and increasing the proportion held as bonds. There is a similar agreement in place for the primary US plan. During 2018, the UK and the US plans switched 12.5% and 10% of plan assets respectively from equities to bonds.
The current asset allocation policy for the major plans at 31 December 2018 was as follows:
 
 
UK
US
Asset category
 
%
%
Total equity (including private equity)
 
30
40
Bonds/cash (including LDI)
 
63
60
Property/real estate
 
7

The amounts invested under the LDI programme by the primary UK pension plan as at 31 December 2018 were $4,197 million (2017 $2,588 million) of government-issued nominal bonds and $17,491 million (2017 $16,177 million) of index-linked bonds.
Some of the group’s pension plans in the Eurozone and other countries use derivative financial instruments as part of their asset mix to manage the level of risk. The fair value of these instruments are included in other assets in the table below. The UK and US plans do not use derivative financial instruments.
The group’s main pension plans do not invest directly in either securities or property/real estate of the company or of any subsidiary.
The fair values of the various categories of assets held by the defined benefit plans at 31 December are presented in the table below, including the effects of derivative financial instruments. Movements in the fair value of plan assets during the year are shown in detail in the table on page 176.
24. Pensions and other post-retirement benefits – continued
 
 
 
 
 
 
$ million

 
 
UKa

USb

Eurozone

Other

Total

Fair value of pension plan assets
 
 
 
 
 
 
At 31 December 2018
 
 
 
 
 
 
Listed equities – developed markets
 
5,191

1,238

413

306

7,148

   – emerging markets
 
950

63

65

56

1,134

Private equityc
 
2,792

1,495


4

4,291

Government issued nominal bondsd
 
4,263

2,072

895

533

7,763

Government issued index-linked bondsd
 
17,491


102


17,593

Corporate bondsd
 
4,606

2,184

506

243

7,539

Propertye
 
2,311

6

57

25

2,399

Cash
 
376

73

42

83

574

Other
 
116

64

32

40

252

Debt (repurchase agreements) used to fund liability driven investments
 
(6,011
)



(6,011
)
 
 
32,085

7,195

2,112

1,290

42,682

At 31 December 2017
 
 
 
 
 
 
Listed equities – developed markets
 
9,548

2,158

537

376

12,619

   – emerging markets
 
2,220

220

83

53

2,576

Private equityc
 
2,679

1,461



4,140

Government issued nominal bondsd
 
2,663

1,777

941

545

5,926

Government issued index-linked bondsd
 
16,177


2


16,179

Corporate bondsd
 
4,682

2,024

546

272

7,524

Propertye
 
2,211

6

71

30

2,318

Cash
 
390

80

21

98

589

Other
 
104

53

23

45

225

Debt (repurchase agreements) used to fund liability driven investments
 
(5,583
)



(5,583
)
 
 
35,091

7,779

2,224

1,419

46,513

At 31 December 2016
 
 
 
 
 
 
Listed equities – developed markets
 
11,494

2,283

436

363

14,576

   – emerging markets
 
2,549

220

54

46

2,869

Private equityc
 
2,754

1,442

1


4,197

Government issued nominal bondsd
 
489

1,438

821

448

3,196

Government issued index-linked bondsd
 
9,384


4


9,388

Corporate bondsd
 
4,042

1,732

427

259

6,460

Propertye
 
1,970

6

45

28

2,049

Cash
 
547

105

17

83

752

Other
 
(68
)
90

74

83

179

Debt (repurchase agreements) used to fund liability driven investments
 
(2,981
)



(2,981
)
 
 
30,180

7,316

1,879

1,310

40,685

a 
Bonds held by the UK pension plans are denominated in sterling. Property held by the UK pension plans is in the United Kingdom.
b 
Bonds held by the US pension plans are denominated in US dollars.
c Private equity is valued at fair value based on the most recent third-party net asset valuation.
d Bonds held by pension plans are valued using quoted prices in active markets. Where quoted prices are not available, quoted prices for similar instruments in active markets are used.
e Properties are valued based on an analysis of recent market transactions supported by market knowledge derived from third-party valuers.
24. Pensions and other post-retirement benefits – continued
 
 
 
 
 
 
$ million

 
 
 
 
 
 
2018

 
 
UK

US

Eurozone

Other

Total

Analysis of the amount charged to profit or loss
 
 
 
 
 
 
Current service costa
 
295

299

84

43

721

Past service costb
 
15


9

4

28

Settlementb
 


17


17

Operating charge relating to defined benefit plans
 
310

299

110

47

766

Payments to defined contribution plans
 
38

178

5

40

261

Total operating charge
 
348

477

115

87

1,027

Interest income on plan assetsa
 
(868
)
(262
)
(44
)
(45
)
(1,219
)
Interest on plan liabilities
 
774

369

136

67

1,346

Other finance (income) expense
 
(94
)
107

92

22

127

Analysis of the amount recognized in other comprehensive income
 
 
 
 
 
 
Actual asset return less interest income on plan assets
 
(722
)
(256
)
(69
)
(36
)
(1,083
)
Change in financial assumptions underlying the present value of the plan liabilities
 
1,770

945

14

65

2,794

Change in demographic assumptions underlying the present value of the plan liabilities
 
123

(9
)
(42
)
7

79

Experience gains and losses arising on the plan liabilities
 
520

41

(43
)
9

527

Remeasurements recognized in other comprehensive income
 
1,691

721

(140
)
45

2,317

Movements in benefit obligation during the year
 
 
 
 
 
 
Benefit obligation at 1 January
 
31,513

10,820

7,275

1,873

51,481

Exchange adjustments
 
(1,589
)

(303
)
(113
)
(2,005
)
Operating charge relating to defined benefit plans
 
310

299

110

47

766

Interest cost
 
774

369

136

67

1,346

Contributions by plan participantsc
 
21


2

7

30

Benefit payments (funded plans)d
 
(1,780
)
(597
)
(84
)
(83
)
(2,544
)
Benefit payments (unfunded plans)d
 
(6
)
(218
)
(301
)
(17
)
(542
)
Disposals
 



(14
)
(14
)
Remeasurements
 
(2,413
)
(977
)
71

(81
)
(3,400
)
Benefit obligation at 31 Decembera e
 
26,830

9,696

6,906

1,686

45,118

Movements in fair value of plan assets during the year
 





Fair value of plan assets at 1 January
 
35,091

7,779

2,224

1,419

46,513

Exchange adjustments
 
(1,883
)

(93
)
(73
)
(2,049
)
Interest income on plan assetsa f
 
868

262

44

45

1,219

Contributions by plan participantsc
 
21


2

7

30

Contributions by employers (funded plans)
 
490

7

88

25

610

Benefit payments (funded plans)d
 
(1,780
)
(597
)
(84
)
(83
)
(2,544
)
Disposals
 



(14
)
(14
)
Remeasurementsf
 
(722
)
(256
)
(69
)
(36
)
(1,083
)
Fair value of plan assets at 31 Decemberg
 
32,085

7,195

2,112

1,290

42,682

Surplus (deficit) at 31 December
 
5,255

(2,501
)
(4,794
)
(396
)
(2,436
)
Represented by
 





Asset recognized
 
5,473

418

29

35

5,955

Liability recognized
 
(218
)
(2,919
)
(4,823
)
(431
)
(8,391
)
 
 
5,255

(2,501
)
(4,794
)
(396
)
(2,436
)
The surplus (deficit) may be analysed between funded and unfunded plans as follows
 





Funded
 
5,473

396

(152
)
(97
)
5,620

Unfunded
 
(218
)
(2,897
)
(4,642
)
(299
)
(8,056
)
 
 
5,255

(2,501
)
(4,794
)
(396
)
(2,436
)
The defined benefit obligation may be analysed between funded and unfunded plans as follows
 





Funded
 
(26,612
)
(6,799
)
(2,264
)
(1,387
)
(37,062
)
Unfunded
 
(218
)
(2,897
)
(4,642
)
(299
)
(8,056
)
 
 
(26,830
)
(9,696
)
(6,906
)
(1,686
)
(45,118
)
a 
The costs of managing plan investments are offset against the investment return, the costs of administering pension plan benefits are generally included in current service cost and the costs of administering other post-retirement benefit plans are included in the benefit obligation.
b 
Past service costs and settlements have arisen from restructuring programmes and represent charges for special termination benefits representing the increased liability arising as a result of early retirements mostly in the UK and Eurozone.
c 
Most of the contributions made by plan participants into UK pension plans were made under salary sacrifice.
d 
The benefit payments amount shown above comprises $3,046 million benefits and $2 million settlements, plus $38 million of plan expenses incurred in the administration of the benefit.
e 
The benefit obligation for the US is made up of $7,290 million for pension liabilities and $2,406 million for other post-retirement benefit liabilities (which are unfunded and are primarily retiree medical liabilities). The benefit obligation for the Eurozone includes $4,328 million for pension liabilities in Germany which is largely unfunded.
f 
The actual return on plan assets is made up of the sum of the interest income on plan assets and the remeasurement of plan assets as disclosed above.
g 
The fair value of plan assets includes borrowings related to the LDI programme as described on page 174.
24. Pensions and other post-retirement benefits – continued
 
 
 
 
 
 
$ million

 
 
 
 
 
 
2017

 
 
UK

US

Eurozone

Other

Total

Analysis of the amount charged to profit or loss
 
 
 
 
 
 
Current service costa
 
357

292

85

46

780

Past service costb
 
12


5

(1
)
16

Settlementb
 


13


13

Operating charge relating to defined benefit plans
 
369

292

103

45

809

Payments to defined contribution plans
 
31

191

7

38

267

Total operating charge
 
400

483

110

83

1,076

Interest income on plan assetsa
 
(845
)
(266
)
(37
)
(48
)
(1,196
)
Interest on plan liabilities
 
831

393

121

71

1,416

Other finance (income) expense
 
(14
)
127

84

23

220

Analysis of the amount recognized in other comprehensive income
 
 
 
 
 
 
Actual asset return less interest income on plan assets
 
2,396

826

30

43

3,295

Change in financial assumptions underlying the present value of the plan liabilities
 
(236
)
(514
)
336

(47
)
(461
)
Change in demographic assumptions underlying the present value of the plan liabilities
 
734

72


(23
)
783

Experience gains and losses arising on the plan liabilities
 
91

(40
)
(36
)
14

29

Remeasurements recognized in other comprehensive income
 
2,985

344

330

(13
)
3,646

Movements in benefit obligation during the year
 
 
 
 
 
 
Benefit obligation at 1 January
 
29,908

10,533

6,820

1,715

48,976

Exchange adjustments
 
2,886


915

89

3,890

Operating charge relating to defined benefit plans
 
369

292

103

45

809

Interest cost
 
831

393

121

71

1,416

Contributions by plan participantsc
 
16


2

6

24

Benefit payments (funded plans)d
 
(1,903
)
(641
)
(75
)
(89
)
(2,708
)
Benefit payments (unfunded plans)d
 
(5
)
(239
)
(302
)
(20
)
(566
)
Acquisitions
 

1



1

Disposals
 

(1
)
(9
)

(10
)
Remeasurements
 
(589
)
482

(300
)
56

(351
)
Benefit obligation at 31 Decembera e
 
31,513

10,820

7,275

1,873

51,481

Movements in fair value of plan assets during the year
 
 
 
 
 
 
Fair value of plan assets at 1 January
 
30,180

7,316

1,879

1,310

40,685

Exchange adjustments
 
3,048


264

72

3,384

Interest income on plan assetsa f
 
845

266

37

48

1,196

Contributions by plan participantsc
 
16


2

6

24

Contributions by employers (funded plans)
 
509

12

87

29

637

Benefit payments (funded plans)d
 
(1,903
)
(641
)
(75
)
(89
)
(2,708
)
Remeasurementsf
 
2,396

826

30

43

3,295

Fair value of plan assets at 31 Decemberg
 
35,091

7,779

2,224

1,419

46,513

Surplus (deficit) at 31 December
 
3,578

(3,041
)
(5,051
)
(454
)
(4,968
)
Represented by
 
 
 
 
 
 
Asset recognized
 
3,838

260

43

28

4,169

Liability recognized
 
(260
)
(3,301
)
(5,094
)
(482
)
(9,137
)
 
 
3,578

(3,041
)
(5,051
)
(454
)
(4,968
)
The surplus (deficit) may be analysed between funded and unfunded plans as follows
 
 
 
 
 
 
Funded
 
3,838

238

(106
)
(101
)
3,869

Unfunded
 
(260
)
(3,279
)
(4,945
)
(353
)
(8,837
)
 
 
3,578

(3,041
)
(5,051
)
(454
)
(4,968
)
The defined benefit obligation may be analysed between funded and unfunded plans as follows
 
 
 
 
 
 
Funded
 
(31,253
)
(7,541
)
(2,330
)
(1,520
)
(42,644
)
Unfunded
 
(260
)
(3,279
)
(4,945
)
(353
)
(8,837
)
 
 
(31,513
)
(10,820
)
(7,275
)
(1,873
)
(51,481
)
a 
The costs of managing plan investments are offset against the investment return, the costs of administering pension plan benefits are generally included in current service cost and the costs of administering other post-retirement benefit plans are included in the benefit obligation.
b 
Past service costs and settlements have arisen from restructuring programmes and represent charges for special termination benefits representing the increased liability arising as a result of early retirements mostly in the UK and Eurozone.
c 
Most of the contributions made by plan participants into UK pension plans were made under salary sacrifice.
d 
The benefit payments amount shown above comprises $3,235 million benefits and $2 million settlements, plus $37 million of plan expenses incurred in the administration of the benefit.
e 
The benefit obligation for the US is made up of $8,085 million for pension liabilities and $2,735 million for other post-retirement benefit liabilities (which are unfunded and are primarily retiree medical liabilities). The benefit obligation for the Eurozone includes $4,586 million for pension liabilities in Germany which is largely unfunded.
f 
The actual return on plan assets is made up of the sum of the interest income on plan assets and the remeasurement of plan assets as disclosed above.
g 
The fair value of plan assets includes borrowings related to the LDI programme as described on page 174.
24. Pensions and other post-retirement benefits – continued
 
 
 
 
 
 
$ million

 
 
 
 
 
 
2016

 
 
UK

US

Eurozone

Other

Total

Analysis of the amount charged to profit or loss
 
 
 
 
 
 
Current service costa
 
333

310

76

71

790

Past service costb
 
17

(24
)
7

1

1

Settlement
 


9

(1
)
8

Operating charge relating to defined benefit plans
 
350

286

92

71

799

Payments to defined contribution plans
 
30

194

7

33

264

Total operating charge
 
380

480

99

104

1,063

Interest income on plan assetsa
 
(1,086
)
(287
)
(47
)
(51
)
(1,471
)
Interest on plan liabilities
 
1,005

417

159

80

1,661

Other finance (income) expense
 
(81
)
130

112

29

190

Analysis of the amount recognized in other comprehensive income
 
 
 
 
 
 
Actual asset return less interest income on plan assets
 
4,422

330

53

8

4,813

Change in financial assumptions underlying the present value of the plan liabilities
 
(6,932
)
(239
)
(622
)
4

(7,789
)
Change in demographic assumptions underlying the present value of the plan liabilities
 
430

9

12

(5
)
446

Experience gains and losses arising on the plan liabilities
 
55

(62
)
26

15

34

Remeasurements recognized in other comprehensive income
 
(2,025
)
38

(531
)
22

(2,496
)
a The costs of managing plan investments are offset against the investment return, the costs of administering pension plan benefits are generally included in current service cost and the costs of administering other post-retirement benefit plans are included in the benefit obligation.
b Past service costs have arisen from restructuring programmes and represent a combination of credits as a result of the curtailment in the pension arrangements of a number of employees mostly in the US and charges for special termination benefits representing the increased liability arising as a result of early retirements mostly in the UK and Eurozone. The UK also includes $12 million of cost resulting from benefit harmonization within the primary plan.

Sensitivity analysis
The discount rate, inflation, salary growth and the mortality assumptions all have a significant effect on the amounts reported. A one-percentage point change, in isolation, in certain assumptions as at 31 December 2018 for the group’s plans would have had the effects shown in the table below. The effects shown for the expense in 2019 comprise the total of current service cost and net finance income or expense.
 
 
 
$ million

 
 
One percentage point
 
 
 
Increase

Decrease

Discount ratea
 
 
 
Effect on pension and other post-retirement benefit expense in 2019
 
(337
)
295

Effect on pension and other post-retirement benefit obligation at 31 December 2018
 
(6,179
)
8,153

Inflation rateb
 
 
 
Effect on pension and other post-retirement benefit expense in 2019
 
227

(187
)
Effect on pension and other post-retirement benefit obligation at 31 December 2018
 
4,919

(4,225
)
Salary growth
 
 
 
Effect on pension and other post-retirement benefit expense in 2019
 
64

(55
)
Effect on pension and other post-retirement benefit obligation at 31 December 2018
 
653

(595
)
a 
The amounts presented reflect that the discount rate is used to determine the asset interest income as well as the interest cost on the obligation.
b 
The amounts presented reflect the total impact of an inflation rate change on the assumptions for rate of increase in salaries, pensions in payment and deferred pensions.
One additional year of longevity in the mortality assumptions would increase the 2019 pension and other post-retirement benefit expense by $52 million and the pension and other post-retirement benefit obligation at 31 December 2018 by $1,432 million.
Estimated future benefit payments and the weighted average duration of defined benefit obligations
The expected benefit payments, which reflect expected future service, as appropriate, but exclude plan expenses, up until 2028 and the weighted average duration of the defined benefit obligations at 31 December 2018 are as follows:
 
 
 
 
 
 
$ million

Estimated future benefit payments
 
UK

US

Eurozone

Other

Total

2019
 
1,030

787

350

101

2,268

2020
 
1,036

755

339

97

2,227

2021
 
1,056

806

331

97

2,290

2022
 
1,088

749

326

100

2,263

2023
 
1,120

741

317

98

2,276

2024-2028
 
5,777

3,476

1,501

498

11,252

 
 
 
 
 
 
Years

Weighted average duration
 
17.8

9.5

14.2

13.0

 
Employee costs and numbers
 
 
 
 
$ million

Employee costs
 
2018

2017

2016

Wages and salariesa
 
7,931

7,572

8,456

Social security costs
 
743

711

760

Share-based paymentsb
 
669

624

764

Pension and other post-retirement benefit costs
 
1,154

1,296

1,253

 
 
10,497

10,203

11,233


 
 
 
 
2018

 
 
2017

 
 
2016

Average number of employeesc
 
US

Non-US

Total

US

Non-US

Total

US

Non-US

Total

Upstream
 
5,900

11,500

17,400

6,200

12,200

18,400

6,700

13,500

20,200

Downstreamd e
 
6,000

36,300

42,300

6,100

35,900

42,000

6,600

36,600

43,200

Other businesses and corporatee f
 
1,900

12,100

14,000

1,900

12,400

14,300

1,900

12,100

14,000

 
 
13,800

59,900

73,700

14,200

60,500

74,700

15,200

62,200

77,400

a Includes termination costs of $493 million (2017 $189 million and 2016 $545 million).
b The group provides certain employees with shares and share options as part of their remuneration packages. The majority of these share-based payment arrangements are equity-settled.
c Reported to the nearest 100.
d Includes 17,100 (2017 16,500 and 2016 15,800) service station staff.
e Around 800 centralized function employees were reallocated from Upstream and Downstream to Other businesses and corporate during 2016.
f Includes 4,000 (2017 4,700 and 2016 4,900) agricultural, operational and seasonal workers in Brazil.