operating expenses millions 2010 2009 2008 % (  % ) change 2010 v 2009 % (  % ) change 2009 v 2008 .

2010: compensation and benefits: 4314
fuel: 2486
purchased services and materials: 1836
depreciation: 1487
equipment and other rents: 1142
other: 719
total: 11984
2009: compensation and benefits: 4063
fuel: 1763
purchased services and materials: 1644
depreciation: 1427
equipment and other rents: 1180
other: 687
total: 10764
2008: compensation and benefits: 4457
fuel: 3983
purchased services and materials: 1928
depreciation: 1366
equipment and other rents: 1326
other: 840
total: 13900
% (  % ) change 2010 v 2009: compensation and benefits: -6
fuel: 41
purchased services and materials: 12
depreciation: 4
equipment and other rents: -3
other: 5
total: -11
% (  % ) change2009 v 2008: compensation and benefits: -9
fuel: -56
purchased services and materials: -15
depreciation: 4
equipment and other rents: -11
other: -18
total: -23

operating expenses increased $ 1.2 billion in 2010 versus 2009 . our fuel price per gallon increased 31% ( 31 % ) during the year , accounting for $ 566 million of the increase . wage and benefit inflation , depreciation , volume-related costs , and property taxes also contributed to higher expenses during 2010 compared to 2009 . cost savings from productivity improvements and better resource utilization partially offset these increases . operating expenses decreased $ 3.1 billion in 2009 versus 2008 . our fuel price per gallon declined 44% ( 44 % ) during 2009 , decreasing operating expenses by $ 1.3 billion compared to 2008 . cost savings from lower volume , productivity improvements , and better resource utilization also decreased operating expenses in 2009 . in addition , lower casualty expense resulting primarily from improving trends in safety performance decreased operating expenses in 2009 . conversely , wage and benefit inflation partially offset these reductions . compensation and benefits 2013 compensation and benefits include wages , payroll taxes , health and welfare costs , pension costs , other postretirement benefits , and incentive costs . general wage and benefit inflation increased costs by approximately $ 190 million in 2010 compared to 2009 . volume- related expenses and higher equity and incentive compensation also drove costs up during the year . workforce levels declined 1% ( 1 % ) in 2010 compared to 2009 as network efficiencies and ongoing productivity initiatives enabled us to effectively handle the 13% ( 13 % ) increase in volume levels with fewer employees . lower volume and productivity initiatives led to a 10% ( 10 % ) decline in our workforce in 2009 compared to 2008 , saving $ 516 million during the year . conversely , general wage and benefit inflation increased expenses , partially offsetting these savings . fuel 2013 fuel includes locomotive fuel and gasoline for highway and non-highway vehicles and heavy equipment . higher diesel fuel prices , which averaged $ 2.29 per gallon ( including taxes and transportation costs ) in 2010 compared to $ 1.75 per gallon in 2009 , increased expenses by $ 566 million . volume , as measured by gross ton-miles , increased 10% ( 10 % ) in 2010 versus 2009 , driving fuel expense up by $ 166 million . conversely , the use of newer , more fuel efficient locomotives , our fuel conservation programs and efficient network operations drove a 3% ( 3 % ) improvement in our fuel consumption rate in 2010 , resulting in $ 40 million of cost savings versus 2009 at the 2009 average fuel price . lower diesel fuel prices , which averaged $ 1.75 per gallon ( including taxes and transportation costs ) in 2009 compared to $ 3.15 per gallon in 2008 , reduced expenses by $ 1.3 billion in 2009 . volume , as measured by gross ton-miles , decreased 17% ( 17 % ) in 2009 , lowering expenses by $ 664 million compared to 2008 . our fuel consumption rate improved 4% ( 4 % ) in 2009 , resulting in $ 147 million of cost savings versus 2008 at the 2008 average fuel price . the consumption rate savings versus 2008 using the lower 2009 fuel price was $ 68 million . newer , more fuel efficient locomotives , reflecting locomotive acquisitions in recent years and the impact of a smaller fleet due to storage of some of our older locomotives ; increased use of 2010 operating expenses .

Questions:
what is the sum of operating expense for 2009 and 2010?
what was operating expense in 2008?
what is the total sum including all 3 years?
what is the average per year?

Answers:
22748
13900
36648
12216