(6) Commitments

As of December 31, 2016, Forrester had future contractual obligations as follows for operating leases (in thousands):

2017	$	11,913
2018		11,153
2019		10,775
2020		10,223
2021		8,816
Thereafter		35,943
Total minimum lease payments	$	88,823

The cost of these operating leases, including any contractual rent increases, rent concessions, and landlord incentives, are recognized ratably over the life of the related lease agreement. Aggregate rent expense was $16.1 million, $16.0 million and $15.9 million for the years ended December 31, 2016, 2015, and 2014, respectively.