operating expenses millions 2013 2012 2011 % (  % ) change 2013 v 2012 % (  % ) change 2012 v 2011 .
what percentage of total operating expenses was fuel in 2013?
operating expenses increased $ 336 million in 2013 versus 2012 . wage and benefit inflation , new logistics management fees and container costs for our automotive business , locomotive overhauls , property taxes and repairs on jointly owned property contributed to higher expenses during the year . lower fuel prices partially offset the cost increases . operating expenses increased $ 348 million in 2012 versus 2011 . depreciation , wage and benefit inflation , higher fuel prices and volume- related trucking services purchased by our logistics subsidiaries , contributed to higher expenses during the year . efficiency gains , volume related fuel savings ( 2% ( 2 % ) fewer gallons of fuel consumed ) and $ 38 million of weather related expenses in 2011 , which favorably affects the comparison , partially offset the cost increase . compensation and benefits 2013 compensation and benefits include wages , payroll taxes , health and welfare costs , pension costs , other postretirement benefits , and incentive costs . general wages and benefits inflation , higher work force levels and increased pension and other postretirement benefits drove the increases in 2013 versus 2012 . the impact of ongoing productivity initiatives partially offset these increases . expenses in 2012 were essentially flat versus 2011 as operational improvements and cost reductions offset general wage and benefit inflation and higher pension and other postretirement benefits . in addition , weather related costs increased these expenses in 2011 . fuel 2013 fuel includes locomotive fuel and gasoline for highway and non-highway vehicles and heavy equipment . lower locomotive diesel fuel prices , which averaged $ 3.15 per gallon ( including taxes and transportation costs ) in 2013 , compared to $ 3.22 in 2012 , decreased expenses by $ 75 million . volume , as measured by gross ton-miles , decreased 1% ( 1 % ) while the fuel consumption rate , computed as gallons of fuel consumed divided by gross ton-miles , increased 2% ( 2 % ) compared to 2012 . declines in heavier , more fuel-efficient coal shipments drove the variances in gross-ton-miles and the fuel consumption rate . higher locomotive diesel fuel prices , which averaged $ 3.22 per gallon ( including taxes and transportation costs ) in 2012 , compared to $ 3.12 in 2011 , increased expenses by $ 105 million . volume , as measured by gross ton-miles , decreased 2% ( 2 % ) in 2012 versus 2011 , driving expense down . the fuel consumption rate was flat year-over-year . purchased services and materials 2013 expense for purchased services and materials includes the costs of services purchased from outside contractors and other service providers ( including equipment maintenance and contract expenses incurred by our subsidiaries for external transportation services ) ; materials used to maintain the railroad 2019s lines , structures , and equipment ; costs of operating facilities jointly used by uprr and other railroads ; transportation and lodging for train crew employees ; trucking and contracting costs for intermodal containers ; leased automobile maintenance expenses ; and tools and 2013 operating expenses .