Note 4. Leases

We lease certain assets under operating leases, which primarily consist of real estate leases for 63 of our 221 service center locations at December 31, 2013. 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, 2013 are as follows:



(In thousands)	Total
2014	$	15,931
2015	10,833
2016	7,508
2017	5,684
2018	4,623
Thereafter	14,210
Total minimum lease payments	$	58,789

Aggregate expense under operating leases was $17.9 million, $19.1 million and $19.5 million for 2013, 2012 and 2011, 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, 2013. At December 31, 2012, we leased certain information systems under capital leases with a gross carrying value of $9.9 million and accumulated amortization of $2.3 million.