665,000 Iraqis killed since the "liberation"

According to a study led by Gilbert Burnham of Johns Hopkins University, there have been approximately 655,000 casualties in Iraq since the U.S.-led invasion in March 2003:

Methods Between May and July 2006 a national cluster survey was conducted in Iraq to assess deaths occurring during the period from January 1, 2002, through the time of survey in 2006. Information on deaths from 1,849 households containing 12,801 persons was collected. This survey followed a similar but smaller survey conducted in Iraq in 2004. Both surveys used standard methods for estimating deaths in conflict situations, using population-based methods.

Findings Death rates were 5.5/1000/year pre-invasion, and overall, 13.2/1000/year for the 40 months post-invasion. We estimate that through July 2006, there have been 654,965 “excess deaths”—fatalities above the pre-invasion death rate—in Iraq as a consequence of the war. Of post-invasion deaths, 601,027 were due to violent causes. Non-violent deaths rose above the pre-invasion level only in 2006. Since March 2003, an additional 2.5% of Iraq’s population have died above what would have occurred without conflict.
The proportion of deaths ascribed to coalition forces has diminished in 2006, though the actual numbers have increased each year. Gunfire remains the most common reason for death, though deaths from car bombing have increased from 2005. Those killed are predominantly males aged 15-44 years.

The study is published in The Lancet.

Link: Burnham, G. & Lafta, R. (2006). Mortality after the 2003 invasion of Iraq: A cross-sectional cluster sample survey. The Lancet DOI:10:1016/S0140-6736(06)69491-9.