http://usnews.nbcnews.com/_news/2013/05/07/18108298-gun-violence-in-us-has-fallen-dramatically-over-past-20-years-justice-dept-report-finds?lite
As for where crime guns came from, the study notes that less than two percent - gun shows or flea markets. The highest number, 40 percent, - came from a family member or a friend. 37 percent - stolen or obtained from an illegal source