For the purpose of analysis, the 40 months of survey data were divided into three equal periods—March 2003 to April 2004; May 2004 to May 2005, and June 2005 to June 2006. Following the invasion the death rate rose each year. "Pre-invasion: 5.5 deaths/1,000/year March 2003–April 2004: 7.5 deaths/1,000/year May 2004–May 2005: 10.9 deaths/1,000/year June 2005–June 2006: 19.8 deaths/1,000/year Overall post-invasion: 13.2 deaths/1,000/year