increased by $ 105.6 million , or 3.4% ( 3.4 % ) , from 2006 to 2007 . the following table reflects the components of our revenue growth for the years ended december 31 , 2008 , 2007 and 2006: .
what was the average cost of operations from 2006 to 2008 in millions
( 1 ) core volume growth for the year ended december 31 , 2006 includes .8% ( .8 % ) associated with hauling waste from the city of toronto to one of our landfills in michigan . this hauling service is provided to the city at a rate that approximates our cost . ( 2 ) includes the impact of the acquisition of allied in december 2008 . ( 3 ) represents new taxes levied on landfill volumes in certain states that are passed on to customers . 25aa 2008 : during the year ended december 31 , 2008 , our core revenue growth continued to benefit from a broad-based pricing initiative . in addition , 14.7% ( 14.7 % ) of our revenue growth is due to our acquisition of allied in december 2008 . revenue growth also benefited from higher fuel surcharges and environmental fees . however , during 2008 we experienced lower prices for commodities . we also experienced a decrease in core volumes primarily due to lower commercial and industrial collection volumes and lower landfill volumes resulting from the slowdown in the economy . we expect to continue to experience lower volumes until economic conditions improve . 25aa 2007 : during the year ended december 31 , 2007 , our revenue growth from core pricing continued to benefit from a broad-based pricing initiative . our revenue growth also benefited from higher prices for commodities . however , we experienced a decrease in core volume growth primarily due to lower industrial collection and landfill volumes resulting from the slowdown in residential construction . 25aa 2006 : during the year ended december 31 , 2006 , our revenue growth continued to benefit from our broad-based pricing initiative . we experienced core volume growth in our collection and landfill lines of business . this core volume growth was partially offset by hurricane clean-up efforts that took place during the fourth quarter of 2005 . 25aa 2009 outlook : we anticipate internal revenue from core operations to decrease approximately 4.0% ( 4.0 % ) during 2009 . this decrease is the expected net of growth in core pricing of approximately 4.0% ( 4.0 % ) and an expected decrease in volume of approximately 8.0% ( 8.0 % ) . our projections assume no deterioration or improvement in the overall economy from that experienced during the fourth quarter of 2008 . however , our internal growth may remain flat or may decline in 2009 depending on economic conditions and our success in implementing pricing initiatives . cost of operations . cost of operations was $ 2.4 billion , $ 2.0 billion and $ 1.9 billion , or , as a percentage of revenue , 65.6% ( 65.6 % ) , 63.1% ( 63.1 % ) and 62.7% ( 62.7 % ) , for the years ended december 31 , 2008 , 2007 and 2006 , respectively . the increase in cost of operations in aggregate dollars for the year ended december 31 , 2008 versus the comparable 2007 period is primarily a result of our acquisition of allied in december 2008 . the remaining increase in cost of operations in aggregate dollars and the increase as a percentage of revenue is primarily due to charges we recorded during 2008 of $ 98.0 million related to estimated costs to comply with f&os issued by the oepa and the aoc issued by the epa in response to environmental conditions at our countywide facility in ohio , $ 21.9 million related to environmental conditions at our closed disposal facility %%transmsg*** transmitting job : p14076 pcn : 048000000 ***%%pcmsg|46 |00044|yes|no|02/28/2009 17:08|0|0|page is valid , no graphics -- color : d| .