18.GLYPH<160>Commitments and Contingent Liabilities Operating Leases Operating lease commitments are primarily for office space and equipment. Certain office space leases provide  for rent adjustments relating to changes in real estate taxes and other operating costs. Rental expense amounted to approximately $16 million in 2014  and  2013 and $18 million in 2012. The  approximate minimum rental commitments under noncancelable leases, net of subleases, as of December 28, 2014  were as follows: (In thousands) Amount 2015 $ 12,031 2016 8,582 2017 7,934 2018 4,090 2019 3,026 Later years 9,945 Total minimum lease payments 45,608 Less: noncancelable subleases (4,493) Total minimum lease payments, net of noncancelable subleases $ 41,115 Capital Leases Future minimum lease payments for all capital leases, and the present value of the minimum lease payments as  of December 28, 2014, were as follows: (In thousands) Amount 2015 $ 552 2016 552 2017 552 2018 552 2019 7,245 Later years GLYPH<151> Total minimum lease payments 9,453 Less: imputed interest (2,717) Present value of net minimum lease payments including current maturities $ 6,736 Restricted Cash Newspaper and Mail Deliverers GLYPH<150> PublishersGLYPH<146> Pension Fund  We were required to maintain $30.2 million of restricted cash as of December 28, 2014 and $28.1 million as of  December 29, 2013, primarily related to certain collateral requirements, for obligations under our workers’  compensation programs. These collateral requirements were previously supported by letters of credit under a  revolving credit facility that was replaced in June 2011.  In September 2013, the Newspaper and Mail Deliverers - Publishers’ Pension Fund (the “Fund”) assessed a  partial withdrawal liability to the Company in the amount of $26 million for the plan years ending May 31, 2012 and  2013, an amount that was increased to approximately $34 million in December 2014, when the Fund issued a revised  partial withdrawal liability assessment for the plan year ending May 31, 2013. The Fund claims that when City &  Suburban, a retail and newsstand distribution subsidiary of the Company and the largest contributor to the Fund,  ceased operations in 2009, it triggered a decline of more than 70% in contribution base units in each of these two plan  years. The Company disagrees with both the Fund’s determination that a partial withdrawal occurred and the  methodology by which it calculated the withdrawal liability and has initiated arbitration proceedings. We do not  believe that a loss is probable on this matter and have not recorded a loss contingency for the period ended December  28, 2014. P. 102 – THE NEW YORK TIMES COMPANY