States that implemented "shall-issue" concealed carry laws reduced murders by 8.5%, rapes by 5%, aggravated assaults by 7%, and robbery by 3%, according to a 2000 analysis of FBI crime data by economist and political commentator John R. Lott Jr., PhD. Lott calculated that 1,570 murders, 4,177 rapes, 60,000 aggravated assaults, and 12,000 robberies could have been prevented between 1977 and 1992 if concealed carry had been legal in every US state during that time period. [8] In addition, a 2013 peer-reviewed study in Applied Economic Letters, found that between 1980 and 2009, "states with more restrictive CCW [carrying concealed weapons] laws had gun-related murder rates that were 10% higher." [52] Detroit Chief of Police Larry Craig said permitted concealed weapons are "a deterrent," and "Good Americans with CPLs [concealed permit licenses] translates into crime reduction." [64] A 2013 survey of 15,000 current and retired police officers found that 91.3% support the concealed carry of guns by civilians. [80]