Department of Defense Contractor and Troop Levels in Iraq and Afghanistan: 2007-2016 [August 15, 2016] [open pdf - 634KB]
From the Document: "This report provides background information for Congress on the levels of Department of Defense (DOD) troop and contractor personnel deployed in support of prior and ongoing military operations in Iraq and Afghanistan. For more information on DOD's use of contractor personnel to support military operations, see CRS Report R43074, 'Department of Defense's Use of Contractors to Support Military Operations: Background, Analysis, and Issues for Congress,' by Moshe Schwartz."
CRS Report for Congress, R44116
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html