	As of December 31, 2021			As of December 31, 2020
Revolving credit facility(A)	$	730,000		$	165,407
Interim credit facilities		869,606			—
Term loan		200,000			200,000
British pound sterling term loan(B)		947,240			956,900
Australian term loan facility(B)		871,560			923,280
4.000% Senior Unsecured Notes due 2022(B)		—			610,800
2.550% Senior Unsecured Notes due 2023(B)		541,280			546,800
3.325% Senior Unsecured Notes due 2025(B)		568,500			610,800
0.993% Senior Unsecured Notes due 2026(B)		568,500			—
2.500% Senior Unsecured Notes due 2026(B)		676,600			—
5.250% Senior Unsecured Notes due 2026		500,000			500,000
5.000% Senior Unsecured Notes due 2027		1,400,000			1,400,000
3.692% Senior Unsecured Notes due 2028(B)		811,920			820,200
4.625% Senior Unsecured Notes due 2029		900,000			900,000
3.375% Senior Unsecured Notes due 2030(B)		473,620			—
3.500% Senior Unsecured Notes due 2031		1,300,000			1,300,000
	$	11,358,826		$	8,934,187
Debt issue costs and discount, net		(76,056	)		(68,729	)
	$	11,282,770		$	8,865,458

As of December 31, 2021, principal payments due on our debt (which exclude the effects of any discounts, premiums, or debt issue costs recorded) are as follows (amounts in thousands):

Our current unsecured credit facility (“Credit Facility”) includes a $1.3 billion unsecured revolving loan facility and a $200 million unsecured term loan facility. On January 15, 2021, we amended our Credit Facility. The amendment extended the maturity of our unsecured revolving loan facility to February 1, 2024 and can be extended for an additional 12 months at our option. The maturity date of our term loan facility was extended to February 1, 2026.

In addition to extending the maturity date, the amendment improved interest rate pricing for both facilities. Under the amended Credit Facility and at our election, loans may be made as either ABR Loans or Eurocurrency Loans. The applicable margin for term loans that are ABR Loans is adjustable on a sliding scale from 0.00% to 0.85% based on our current credit rating. The applicable margin for term loans that are Eurocurrency Loans is adjustable on a sliding scale from 0.85% to 1.85% based on our current credit rating. The applicable margin for revolving loans that are ABR Loans is adjustable on a sliding scale from 0.00% to 0.55% based on our current credit rating. The applicable margin for revolving loans that are Eurocurrency Loans is adjustable on a sliding scale from 0.825% to 1.55% based on our current credit rating. The amended Credit Facility retained the facility fee that is adjustable on a sliding scale from 0.125% to 0.30% based on our current credit rating and is payable on the revolving loan facility.

At December 31, 2021, we had $730.0 million outstanding on the revolving credit facility, whereas, we had $165.4 million outstanding on our revolving credit facility at December 31, 2020. At December 31, 2021 and 2020, our availability under our revolving credit facility was $0.6 billion and $1.1 billion, respectively. The weighted-average interest rate on the revolving facility was 1.3% and 1.4% during 2021 and 2020, respectively.

At December 31, 2021 and 2020, the interest rate in effect on our term loan was 1.56% and 1.65%, respectively.

On January 15, 2021, we entered into a $900 million interim credit facility (“January 2021 Interim Credit Facility”), of which we borrowed £500 million to partially fund the Priory Group Transaction. We paid off and terminated this facility on March 26, 2021 with the issuance of the 2.500% Senior Unsecured Notes due 2026 and the 3.375% Senior Unsecured Notes due 2030.

On July 27, 2021, we entered into a $1 billion interim credit facility with Barclays Bank PLC as administrative agent (“July 2021 Interim Credit Facility”), and several lenders from time-to-time are parties thereto. This facility matures on July 28, 2022 and bears interest at a variable rate. We used this facility to partially fund the acquisition of five South Florida facilities in August 2021 and the Springstone investments in October 2021. At December 31, 2021, the outstanding balance under this facility was $869.6 million at a rate of 1.610%.

On January 6, 2020, we entered into a £700 million unsecured sterling-denominated term loan with Bank of America, N.A., as administrative agent, and several lenders from time-to-time are parties thereto. The term loan matures on January 15, 2025. The applicable margin under the term loan is adjustable based on a pricing grid from 0.85% to 1.65% dependent on our current credit rating. On March 4, 2020, we entered into an interest rate swap transaction (effective March 6, 2020) to fix the interest rate to approximately 0.70% for the duration of the loan. The current applicable margin for the pricing grid (which can vary based on our credit rating) is 1.25% for an all-in fixed rate of 1.95%.

On May 23, 2019, we entered into an A$1.2 billion term loan with Bank of America, N.A., as administrative agent, and several lenders from time-to-time are parties thereto. The term loan matures on May 23, 2024. The interest rate under the term loan is adjustable based on a pricing grid from 0.85% to 1.65%, dependent on our current senior unsecured credit rating. On June 27, 2019, we entered into an interest rate swap transaction (effective July 3, 2019) to fix the interest rate to approximately 1.20% for the duration of the loan as long as the reference rate stays above 0.00%. The current applicable margin for the pricing grid (which can vary based on our credit rating) is 1.25% for an all-in fixed rate of 2.45%.

At December 31, 2021, we had a derivative asset of approximately $12.4 million related to the sterling-denominated term loan interest rate swap and a derivative liability of approximately $4.2 million related to the Australian dollar term loan interest rate swap,

included in “Other assets” and "Accounts payable and accrued expenses", respectively, on our consolidated balance sheets. At December 31, 2020, we had a derivative liability of approximately $51.3 million associated with these interest rate swaps, included in “Accounts payable and accrued expenses” on our consolidated balance sheets.

The following are the basic terms of our senior unsecured notes at December 31, 2021 (par value amounts in thousands):

	Offering Completion Date	Maturity Date	Par Value		% of Par Value			Interest Payment Frequency
2.550% Senior Unsecured Notes due 2023	December 5, 2019	December 5, 2023	£	400,000		100.000	%	Annually
3.325% Senior Unsecured Notes due 2025	March 24, 2017	March 24, 2025	€	500,000		100.000	%	Annually
0.993% Senior Unsecured Notes due 2026	October 6, 2021	October 15, 2026	€	500,000		100.000	%	Annually
2.500% Senior Unsecured Notes due 2026	March 24, 2021	March 24, 2026	£	500,000		99.937	%	Annually
5.250% Senior Unsecured Notes due 2026	July 22, 2016	August 1, 2026	$	500,000		100.000	%	Semi-annually
5.000% Senior Unsecured Notes due 2027	September 7, 2017	October 15, 2027	$	1,400,000		100.000	%	Semi-annually
3.692% Senior Unsecured Notes due 2028	December 5, 2019	June 5, 2028	£	600,000		99.998	%	Annually
4.625% Senior Unsecured Notes due 2029	July 26, 2019	August 1, 2029	$	900,000		99.500	%	Semi-annually
3.375% Senior Unsecured Notes due 2030	March 24, 2021	April 24, 2030	£	350,000		99.448	%	Annually
3.500% Senior Unsecured Notes due 2031	December 4, 2020	March 15, 2031	$	1,300,000		100.000	%	Semi-annually

Typically, we may redeem some or all of the notes at any time, but may require a redemption premium that will decrease over time. In the event of a change of control, each holder of the notes may require us to repurchase some or all of our notes at a repurchase price equal to 101% of the aggregate principal amount of the notes plus accrued and unpaid interest to the date of purchase.

With the amendment of our Credit Facility, the termination of our January 2021 Interim Credit Facility, and duration fees incurred on our July 2021 Interim Credit Facility, we incurred approximately $7.3 million of debt refinancing costs in 2021.

With proceeds from our 0.993% Senior Unsecured Notes due 2026 offering, on October 22, 2021, we redeemed all of our outstanding €500 million aggregate principal amount of 4.000% senior unsecured notes that were due in 2022, including accrued and unpaid interest. As a result of this redemption, we incurred a charge of approximately $20 million (including redemption premiums and accelerated amortization of deferred debt issuance costs).

With proceeds from our 3.500% Senior Unsecured Notes due 2031 offering in 2020, we redeemed all of our outstanding $500.0 million aggregate principal amount of 6.375% senior unsecured notes that were due in 2024 and $300.0 million aggregate principal amount of 5.500% senior unsecured notes that were due in 2024, including accrued and unpaid interest. As a result of these redemptions, we incurred a charge of approximately $28 million (including redemption premiums and accelerated amortization of deferred debt issuance costs).

On July 10, 2019, we received a commitment to provide a senior unsecured bridge loan facility to fund our investment in Prospect. With this commitment, we paid approximately $4 million of underwriting and other fees. However, this commitment was cancelled with the completion of the debt and equity offerings in July 2019 (as more fully described in the table above and in Note 9), which resulted in fully expensing the total amount of underwriting and other fees that were paid.

In anticipation of funding our Australian acquisition in June 2019 and the Circle transaction in January 2020, we entered into term loans on the date these deals were signed that had a delayed draw feature. This feature allowed for us to not draw on the term loans until needed to fund these transactions. However, with this type of structure, we incurred approximately $2.0 million in accelerated debt issue cost amortization expense during 2019.

Our debt facilities impose certain restrictions on us, including restrictions on our ability to: incur debts; create or incur liens; provide guarantees in respect of obligations of any other entity; make redemptions and repurchases of our capital stock; prepay, redeem, or repurchase debt; engage in mergers or consolidations; enter into affiliated transactions; dispose of real estate or other assets; and change our business. In addition, the credit agreements governing our Credit Facility limit the amount of dividends we can pay as a percentage of normalized adjusted funds from operations (“NAFFO”), as defined in the agreements, on a rolling four quarter basis. At December 31, 2021, the dividend restriction was 95% of NAFFO. The indentures governing our senior unsecured notes also limit the amount of dividends we can pay based on the sum of 95% of NAFFO, proceeds of equity issuances, and certain other net cash proceeds. Finally, our senior unsecured notes require us to maintain total unencumbered assets (as defined in the related indenture) of not less than 150% of our unsecured indebtedness.

In addition to these restrictions, the Credit Facility contains customary financial and operating covenants, including covenants relating to our total leverage ratio, fixed charge coverage ratio, secured leverage ratio, consolidated adjusted net worth, unsecured leverage ratio, and unsecured interest coverage ratio. The Credit Facility also contains customary events of default, including among others, nonpayment of principal or interest, material inaccuracy of representations, and failure to comply with our covenants. If an event of default occurs and is continuing under the Credit Facility, the entire outstanding balance may become immediately due and payable. At December 31, 2021, we were in compliance with all such financial and operating covenants.