amount of commitment expiration per period other commercial commitments after millions total 2013 2014 2015 2016 2017 2017 .
[['other commercial commitmentsmillions', 'total', 'amount of commitment expiration per period 2013', 'amount of commitment expiration per period 2014', 'amount of commitment expiration per period 2015', 'amount of commitment expiration per period 2016', 'amount of commitment expiration per period 2017', 'amount of commitment expiration per period after 2017'], ['credit facilities [a]', '$ 1800', '$ -', '$ -', '$ 1800', '$ -', '$ -', '$ -'], ['receivables securitization facility [b]', '600', '600', '-', '-', '-', '-', '-'], ['guarantees [c]', '307', '8', '214', '12', '30', '10', '33'], ['standby letters of credit [d]', '25', '24', '1', '-', '-', '-', '-'], ['total commercialcommitments', '$ 2732', '$ 632', '$ 215', '$ 1812', '$ 30', '$ 10', '$ 33']]
[a] none of the credit facility was used as of december 31 , 2012 .[b] $ 100 million of the receivables securitization facility was utilized at december 31 , 2012 , which is accounted for as debt .the full program matures in july 2013 .[c] includes guaranteed obligations related to our headquarters building , equipment financings , and affiliated operations .[d] none of the letters of credit were drawn upon as of december 31 , 2012 .off-balance sheet arrangements guarantees 2013 at december 31 , 2012 , we were contingently liable for $ 307 million in guarantees .we have recorded a liability of $ 2 million for the fair value of these obligations as of december 31 , 2012 and 2011 .we entered into these contingent guarantees in the normal course of business , and they include guaranteed obligations related to our headquarters building , equipment financings , and affiliated operations .the final guarantee expires in 2022 .we are not aware of any existing event of default that would require us to satisfy these guarantees .we do not expect that these guarantees will have a material adverse effect on our consolidated financial condition , results of operations , or liquidity .other matters labor agreements 2013 approximately 86% ( 86 % ) of our 45928 full-time-equivalent employees are represented by 14 major rail unions .during the year , we concluded the most recent round of negotiations , which began in 2010 , with the ratification of new agreements by several unions that continued negotiating into 2012 .all of the unions executed similar multi-year agreements that provide for higher employee cost sharing of employee health and welfare benefits and higher wages .the current agreements will remain in effect until renegotiated under provisions of the railway labor act .the next round of negotiations will begin in early 2015 .inflation 2013 long periods of inflation significantly increase asset replacement costs for capital-intensive companies .as a result , assuming that we replace all operating assets at current price levels , depreciation charges ( on an inflation-adjusted basis ) would be substantially greater than historically reported amounts .derivative financial instruments 2013 we may use derivative financial instruments in limited instances to assist in managing our overall exposure to fluctuations in interest rates and fuel prices .we are not a party to leveraged derivatives and , by policy , do not use derivative financial instruments for speculative purposes .derivative financial instruments qualifying for hedge accounting must maintain a specified level of effectiveness between the hedging instrument and the item being hedged , both at inception and throughout the hedged period .we formally document the nature and relationships between the hedging instruments and hedged items at inception , as well as our risk-management objectives , strategies for undertaking the various hedge transactions , and method of assessing hedge effectiveness .changes in the fair market value of derivative financial instruments that do not qualify for hedge accounting are charged to earnings .we may use swaps , collars , futures , and/or forward contracts to mitigate the risk of adverse movements in interest rates and fuel prices ; however , the use of these derivative financial instruments may limit future benefits from favorable price movements .market and credit risk 2013 we address market risk related to derivative financial instruments by selecting instruments with value fluctuations that highly correlate with the underlying hedged item .we manage credit risk related to derivative financial instruments , which is minimal , by requiring high credit standards for counterparties and periodic settlements .at december 31 , 2012 and 2011 , we were not required to provide collateral , nor had we received collateral , relating to our hedging activities. .

Question: what percentage of total commercial commitments are credit facilities?
Answer: 66%