A relevant article in the Wash Post today:

There are about 100,000 government contractors operating in Iraq, not counting subcontractors, a total that is approaching the size of the U.S. military force there, according to the military's first census of the growing population of civilians operating in the battlefield.

The survey finding, which includes Americans, Iraqis and third-party nationals hired by companies operating under U.S. government contracts, is significantly higher and wider in scope than the Pentagon's only previous estimate, which said there were 25,000 security contractors in the country.

It is also 10 times the estimated number of contractors that deployed during the Persian Gulf War in 1991, reflecting the Pentagon's growing post-Cold War reliance on contractors for such jobs as providing security, interrogating prisoners, cooking meals, fixing equipment and constructing bases that were once reserved for soldiers.

Official numbers are difficult to find, said Deborah D. Avant, author of the 2005 book "The Market for Force: The Consequences of Privatizing Security," but an estimated 9,200 contractors deployed during the Gulf War, a far shorter conflict without reconstruction projects. "This is the largest deployment of U.S. contractors in a military operation," said Avant, an associate professor at George Washington University.
Best

Tom