debt maturities 2013 the following table presents aggregate debt maturities as of december 31 , 2011 , excluding market value adjustments : millions .

Table: 2012 $ 309 2013 636 2014 706 2015 467 2016 517 thereafter 6271 total debt $ 8906

as of both december 31 , 2011 and december 31 , 2010 , we have reclassified as long-term debt approximately $ 100 million of debt due within one year that we intend to refinance . this reclassification reflects our ability and intent to refinance any short-term borrowings and certain current maturities of long- term debt on a long-term basis . mortgaged properties 2013 equipment with a carrying value of approximately $ 2.9 billion and $ 3.2 billion at december 31 , 2011 and 2010 , respectively , served as collateral for capital leases and other types of equipment obligations in accordance with the secured financing arrangements utilized to acquire such railroad equipment . as a result of the merger of missouri pacific railroad company ( mprr ) with and into uprr on january 1 , 1997 , and pursuant to the underlying indentures for the mprr mortgage bonds , uprr must maintain the same value of assets after the merger in order to comply with the security requirements of the mortgage bonds . as of the merger date , the value of the mprr assets that secured the mortgage bonds was approximately $ 6.0 billion . in accordance with the terms of the indentures , this collateral value must be maintained during the entire term of the mortgage bonds irrespective of the outstanding balance of such bonds . credit facilities 2013 during the second quarter of 2011 , we replaced our $ 1.9 billion revolving credit facility , which was scheduled to expire in april 2012 , with a new $ 1.8 billion facility that expires in may 2015 ( the facility ) . the facility is based on substantially similar terms as those in the previous credit facility . on december 31 , 2011 , we had $ 1.8 billion of credit available under the facility , which is designated for general corporate purposes and supports the issuance of commercial paper . we did not draw on either facility during 2011 . commitment fees and interest rates payable under the facility are similar to fees and rates available to comparably rated , investment-grade borrowers . the facility allows for borrowings at floating rates based on london interbank offered rates , plus a spread , depending upon our senior unsecured debt ratings . the facility requires the corporation to maintain a debt-to-net-worth coverage ratio as a condition to making a borrowing . at december 31 , 2011 , and december 31 , 2010 ( and at all times during the year ) , we were in compliance with this covenant . the definition of debt used for purposes of calculating the debt-to-net-worth coverage ratio includes , among other things , certain credit arrangements , capital leases , guarantees and unfunded and vested pension benefits under title iv of erisa . at december 31 , 2011 , the debt-to-net-worth coverage ratio allowed us to carry up to $ 37.2 billion of debt ( as defined in the facility ) , and we had $ 9.5 billion of debt ( as defined in the facility ) outstanding at that date . under our current capital plans , we expect to continue to satisfy the debt-to-net-worth coverage ratio ; however , many factors beyond our reasonable control ( including the risk factors in item 1a of this report ) could affect our ability to comply with this provision in the future . the facility does not include any other financial restrictions , credit rating triggers ( other than rating-dependent pricing ) , or any other provision that could require us to post collateral . the facility also includes a $ 75 million cross-default provision and a change-of-control provision . during 2011 , we did not issue or repay any commercial paper and , at december 31 , 2011 , we had no commercial paper outstanding . outstanding commercial paper balances are supported by our revolving credit facility but do not reduce the amount of borrowings available under the facility . dividend restrictions 2013 our revolving credit facility includes a debt-to-net worth covenant ( discussed in the credit facilities section above ) that , under certain circumstances , restricts the payment of cash .

Question: at december 31 , 2011 , what is the additional borrowing capacity in billions pursuant to the current debt coverage restrictions?
Answer: 27.7
Calculation: subtract(37.2, 9.5)