Cancel 2016.2
The Almighty
It's not there.
Also, too, the National Gang Center says there were 1,824 total gang homocides in 2011 (not just gang homocides using firearms). With 11,101 total gun homicides in 2011, that puts the percentage, at most, to be about 16%, not 71%. But hey, you're only off by 55%.
https://www.nationalgangcenter.gov/Survey-Analysis/Measuring-the-Extent-of-Gang-Problems
what is their source?