A survey of over 1,800 Iraqi households found that approximately 600,000 Iraqis have died since the US-led invasion of Iraq in 2003. The survey was conducted by Iraqi doctors who were trained in public health research methods and interviewed households across Iraq between May and July 2006. It estimated that over 80% of deaths were due to violence, including gunfire and car bombings, with most victims being men between the ages of 15 and 44.