NOTE 10. RENTAL INCOME

During the nine months ended September 30, 2017, approximately 93% of rental income was related to residential apartments and condominium units with leases of one year or less. The majority of these leases expire in June, July and August. Approximately 7% was related to commercial properties, which have minimum future annual rental income on non-cancellable operating leases at September 30, 2017 as follows:


	Commercial
	Property Leases
2018	$	2,697,000
2019		2,248,000
2020		1,687,000
2021		1,396,000
2022		570,000
Thereafter		313,000
	$	8,911,000

The aggregate minimum future rental income does not include contingent rentals that may be received under various leases in connection with common area charges and real estate taxes. Aggregate contingent rentals from continuing operations were approximately $495,000 and $444,000 for the nine months ended September 30, 2017 and 2016 respectively. Staples and Trader Joes, tenants at Staples Plaza, are approximately 31% of the total commercial rental income.

The following information is provided for commercial leases:


	Annual base				Percentage of
	rent for		Total square feet	Total number of	annual base rent for
Throguh September 30,	expiring leases		for expiring leases	leases expiring	expiring leases
2018	$	468,209	18,003	12	16	%
2019		672,327	24,179	12	23	%
2020		215,902	6,428	6	7	%
2021		791,294	34,511	7	27	%
2022		519,397	16,343	6	17	%
2023		58,500	1,950	1	2	%
2024		251,627	6,629	2	8	%
2025		—	—	—	0	%
2026		—	—	—	0	%
2027		—	—	—	0	%
Totals	$	2,977,256	108,043	46	100	%

Rents receivable are net of an allowance for doubtful accounts of approximately $801,000 and $523,000 at September 30, 2017 and December 31, 2016. Included in rents receivable at September 30, 2017 is approximately $130,000 resulting from recognizing rental income from non-cancelable commercial leases with future rental increases on a straight-line basis. The majority of this amount is for long-term leases at 62 Boylston Street in Boston, Massachusetts.

Rents receivable at September 30, 2017 also includes approximately $95,000 representing the deferral of rental concession primarily related to the residential properties.