text: The increase in aggregate dollars in all periods presented is primarily a result of the expansion of our 
  operations through internal growth and acquisitions. 
  
  The increase in cost of operations as a percentage of revenue from 2002 to 2003 and the decrease in cost 
  of operations as a percentage of revenue from 2003 to 2004 is primarily attributable to higher self-insurance 
  expense in 2003. Self-insurance expense was $165.3 million, $189.5 million and $138.1 million for the years 
  ended December 31, 2004, 2003 and 2002, respectively. The increase in self-insurance expense in 2003 related 
  to existing claims and was attributable to the expansion of our operations and various changes in estimates as a 
  result of continued negative trends through the 2003 policy year. 
  
  Excluding self-insurance expense, cost of operations as a percentage of revenue increased during the year 
  ended December 31, 2004 versus the comparable 2003 period. This increase is primarily attributable to 
  increased fuel prices, labor costs and subcontracting costs associated with the long-haul transport of waste by 
  third-party vendors. Excluding self-insurance expense, cost of operations as a percentage of revenue decreased 
  in 2003 versus the comparable 2002 period due to the elimination of closure and post-closure expense as a 
  component of cost of operations in accordance with SFAS 143 in 2003 and the termination of our operating 
  lease facility in July 2002. This decrease was partially oÅset by increased fuel prices, an increase in waste taxes 
  levied on landÑll volumes in certain states, an increase in revenue generated by lines of business that produce 
  lower operating margins and an increase in the long-haul transport of waste by third-party vendors. 