Congressional Budget Office: Contractors’ Support of U.S. Operations in Iraq, August 2008.

• “From 2003 through 2007, U.S. agencies awarded $85 billion in contracts for work to be principally performed in the Iraq theater, accounting for almost 20 percent of funding for operations in Iraq. (Dollar amounts in this paper are in 2008 dollars.) More than 70 percent of those awards were for contracts performed in Iraq itself.”
• “The United States has used contractors during previous military operations, although not to the current extent. According to rough historical data, the ratio of about one contractor employee for every member of the U.S. armed forces in the Iraq theater is at least 2.5 times higher than that ratio during any other major U.S. conflict, although it is roughly comparable with the ratio during operations in the Balkans in the 1990s.”