In 1983, a cross-sectional study of all 50 U.S. states found that the six states with the strictest gun laws (according to the National Rifle Association) had suicide rates that were approximately 3/100,000 people lower than in other states, and that these states' suicide rates were 4/100,000 people lower than those of states with the least restrictive gun laws.[36] A 2003 study published in the American Journal of Preventive Medicine looked at the restrictiveness of gun laws and suicide rates in men and women in all 50 U.S. states and found that states whose gun laws were more restrictive had lower suicide rates among both sexes.[37] In 2004, another study found that the effect of state gun laws on gun-related homicides was "limited".[38] A 2005 study looked at all 50 states in the U.S. and the District of Columbia, and found that no gun laws were associated with reductions in firearm homicide or suicide, but that a "shall-issue" concealed carry law may be associated with increased firearm homicide rates.[39] A 2011 study found that firearm regulation laws in the United States have "a significant deterrent effect on male suicide".[40]