From the Summary: "This report presents various governmental and non-governmental estimates of Iraqi police and security forces fatalities. The Department of Defense (DOD) regularly updates total U.S. military deaths and wounded statistics from Operation Iraqi Freedom (OIF), as reflected in CRS [Congressional Research Service] Report RS21578, 'Iraq: U.S. Casualties', by Susan G. Chesser, and has released the monthly pattern of Iraqi security forces deaths. For information on Iraqi civilian deaths, see CRS Report RS22537, 'Iraqi Civilian Deaths Estimates', by Hannah Fischer. Because these estimates are based on varying time periods and have been created using differing methodologies, readers should exercise caution when using them and should look on them as guideposts rather than as statements of fact. This report will be updated as needed."
CRS Report for Congress, RS22532
Congressional Research Service: https://crsreports.congress.gov/