NOTE 13 . COMMITMENTS AND CONTINGENCIES OPERATING LEASES Minimum future rental payments under operating leases over the next five years and thereafter are as follows: Minimum Payments Under Operating Leases (In millions) 2013 $ 5.3 2014 5.5 2015 5.3 2016 4.3 2017 3.8 Thereafter 4.2 Total $ 28.4 Rent expense totaled $ 5.2 million , $ 5.0 million and $ 4.4 million in fiscal years ended September 30, 2012 , 2011 and 2010 , respectively . REGULATED UTILITY OPERATIONS Natural Gas Contracts Minimum Commitments At September 30, 2012 , Washington Gas had service agreements with four pipeline companies that provide direct service for firm transportation and/or storage services. These agreements, which have expiration dates ranging from fiscal years 2013 to 2029 , require Washington Gas to pay fixed charges each month. Additionally, Washington Gas had agreements for other pipeline and peaking services with expiration dates ranging from 2013 to 2027 . These agreements were entered into based on current estimates of growth of the Washington Gas system, together with other factors, such as current expectations of the timing and extent of unbundling initiatives in the Washington Gas service territory. The following table summarizes the minimum contractual payments that Washington Gas will make under its pipeline transportation, storage and peaking contracts during the next five fiscal years and thereafter. Washington Gas Contract Minimums (In millions) Pipeline Contracts 2013 $ 191.3 2014 188.8 2015 183.2 2016 176.3 2017 168.5 Thereafter 1,076.6 Total $ 1,984.7 Not included in the table above are short-term minimum commitments of $124.4 million to purchase natural gas in fiscal year 2013 at prices based on market conditions at the time the natural gas is purchased. These commitments relate to purchases of natural gas to serve utility customers. Additionally, excluded from the table above are purchases under our asset optimization program totaling 1,021.0 million therms from 2013-2022, which are partially offset by matching sal