Across the United States, if someone is injured in an auto accident, the chances are about one in seven that the at-fault driver is uninsured. According to a recent Insurance Research Council (IRC) study, the estimated percentage of uninsured motorists increased nationally from 12.7 percent in 1999 to 14.6 percent in 2004. However, the magnitude of the uninsured motorists problem varied widely from state to state. The recently released study, Uninsured Motorists, 2006 Edition, examines trends from 1999 to 2004 in the percentage of uninsured drivers by state. In 2004, the five states with the highest uninsured driver estimates were Mississippi (26 percent), Alabama (25 percent), California (25 percent), New Mexico (24 percent), and Arizona (22 percent). The five states with the lowest uninsured driver estimates were Maine (4 percent), Vermont (6 percent), Massachusetts (6 percent), New York (7 percent), and Nebraska (8 percent). IRC estimates the uninsured driver population using a ratio of insurance claims made by individuals who were injured by uninsured drivers to claims made by individuals who were injured by insured drivers.