operating expenses millions 2012 2011 2010 % (  % ) change 2012 v 2011 % (  % ) change 2011 v 2010 .
what percentage of total operating expenses was purchased services and materials in 2012?
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 . operating expenses increased $ 1.8 billion in 2011 versus 2010 . our fuel price per gallon rose 36% ( 36 % ) during 2011 , accounting for $ 922 million of the increase . wage and benefit inflation , volume-related costs , depreciation , and property taxes also contributed to higher expenses . expenses increased $ 20 million for costs related to the flooding in the midwest and $ 18 million due to the impact of severe heat and drought in the south , primarily texas . cost savings from productivity improvements and better resource utilization partially offset these increases . a $ 45 million one-time payment relating to a transaction with csx intermodal , inc ( csxi ) increased operating expenses during the first quarter of 2010 , which favorably affects the comparison of operating expenses in 2011 to those in 2010 . compensation and benefits 2013 compensation and benefits include wages , payroll taxes , health and welfare costs , pension costs , other postretirement benefits , and incentive costs . 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 . a combination of general wage and benefit inflation , volume-related expenses , higher training costs associated with new hires , additional crew costs due to speed restrictions caused by the midwest flooding and heat and drought in the south , and higher pension expense drove the increase during 2011 compared to 2010 . fuel 2013 fuel includes locomotive fuel and gasoline for highway and non-highway vehicles and heavy equipment . 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 . higher locomotive diesel fuel prices , which averaged $ 3.12 ( including taxes and transportation costs ) in 2011 , compared to $ 2.29 per gallon in 2010 , increased expenses by $ 922 million . in addition , higher gasoline prices for highway and non-highway vehicles also increased year-over-year . volume , as measured by gross ton-miles , increased 5% ( 5 % ) in 2011 versus 2010 , driving expense up by $ 122 million . 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 2012 operating expenses .