average cost of debt from 7.1% ( 7.1 % ) to an effective rate of 6.9% ( 6.9 % ) . the inclusion of the offsetting interest income from short-term investments reduced this effective rate to 6.26% ( 6.26 % ) . other financing activities during 2011 included the issuance of approximately 0.3 million shares of treasury stock for various incentive plans and the acquisition of 1.0 million shares of treasury stock primarily related to restricted stock withholding taxes . payments of restricted stock withholding taxes totaled $ 30 million . off-balance sheet variable interest entities information concerning off-balance sheet variable interest entities is set forth in note 12 variable interest entities and preferred securities of subsidiaries on pages 72 through 75 of item 8 . financial statements and supplementary data for discussion . liquidity and capital resources outlook for 2014 capital expenditures and long-term debt international paper expects to be able to meet projected capital expenditures , service existing debt and meet working capital and dividend requirements during 2014 through current cash balances and cash from operations . additionally , the company has existing credit facilities totaling $ 2.0 billion . the company was in compliance with all its debt covenants at december 31 , 2013 . the company 2019s financial covenants require the maintenance of a minimum net worth of $ 9 billion and a total debt-to- capital ratio of less than 60% ( 60 % ) . net worth is defined as the sum of common stock , paid-in capital and retained earnings , less treasury stock plus any cumulative goodwill impairment charges . the calculation also excludes accumulated other comprehensive income/ loss and nonrecourse financial liabilities of special purpose entities . the total debt-to-capital ratio is defined as total debt divided by the sum of total debt plus net worth . at december 31 , 2013 , international paper 2019s net worth was $ 15.1 billion , and the total-debt- to-capital ratio was 39% ( 39 % ) . the company will continue to rely upon debt and capital markets for the majority of any necessary long-term funding not provided by operating cash flows . funding decisions will be guided by our capital structure planning objectives . the primary goals of the company 2019s capital structure planning are to maximize financial flexibility and preserve liquidity while reducing interest expense . the majority of international paper 2019s debt is accessed through global public capital markets where we have a wide base of investors . maintaining an investment grade credit rating is an important element of international paper 2019s financing strategy . at december 31 , 2013 , the company held long-term credit ratings of bbb ( stable outlook ) and baa3 ( stable outlook ) by s&p and moody 2019s , respectively . contractual obligations for future payments under existing debt and lease commitments and purchase obligations at december 31 , 2013 , were as follows: .
in 2015 what percentage of contractual obligations for future payments under existing debt and lease commitments and purchase obligations at december 31 , 2013 was attributable to maturities of long-term debt?
( a ) total debt includes scheduled principal payments only . ( b ) represents debt obligations borrowed from non-consolidated variable interest entities for which international paper has , and intends to effect , a legal right to offset these obligations with investments held in the entities . accordingly , in its consolidated balance sheet at december 31 , 2013 , international paper has offset approximately $ 5.2 billion of interests in the entities against this $ 5.2 billion of debt obligations held by the entities ( see note 12 variable interest entities and preferred securities of subsidiaries on pages 72 through 75 in item 8 . financial statements and supplementary data ) . ( c ) includes $ 3.3 billion relating to fiber supply agreements entered into at the time of the 2006 transformation plan forestland sales and in conjunction with the 2008 acquisition of weyerhaeuser company 2019s containerboard , packaging and recycling business . ( d ) not included in the above table due to the uncertainty as to the amount and timing of the payment are unrecognized tax benefits of approximately $ 146 million . we consider the undistributed earnings of our foreign subsidiaries as of december 31 , 2013 , to be indefinitely reinvested and , accordingly , no u.s . income taxes have been provided thereon . as of december 31 , 2013 , the amount of cash associated with indefinitely reinvested foreign earnings was approximately $ 900 million . we do not anticipate the need to repatriate funds to the united states to satisfy domestic liquidity needs arising in the ordinary course of business , including liquidity needs associated with our domestic debt service requirements . pension obligations and funding at december 31 , 2013 , the projected benefit obligation for the company 2019s u.s . defined benefit plans determined under u.s . gaap was approximately $ 2.2 billion higher than the fair value of plan assets . approximately $ 1.8 billion of this amount relates to plans that are subject to minimum funding requirements . under current irs funding rules , the calculation of minimum funding requirements differs from the calculation of the present value of plan benefits ( the projected benefit obligation ) for accounting purposes . in december 2008 , the worker , retiree and employer recovery act of 2008 ( wera ) was passed by the u.s . congress which provided for pension funding relief and technical corrections . funding .