Note 3. Leases

We lease certain assets under operating leases, which primarily consist of real estate leases for 46 of our 222 service center locations at December 31, 2014. Certain operating leases provide for renewal options, which can vary by lease and are typically offered at their fair rental value. We have not made any residual value guarantees related to our operating leases; therefore, we have no corresponding liability recorded on our Balance Sheets.

Future minimum annual lease payments for assets under operating leases as of December 31, 2014 are as follows:



(In thousands)	Total
2015	$	13,956
2016	10,438
2017	7,522
2018	5,411
2019	2,784
Thereafter	10,671
Total minimum lease payments	$	50,782

Aggregate expense under operating leases was $16.5 million, $17.9 million and $19.1 million for 2014, 2013 and 2012, respectively. Certain operating leases include rent escalation provisions, which we recognize as expense on a straight-line basis. We did not have any assets under capital leases at December 31, 2014 or December 31, 2013.