There were, on average, 16.4 such shootings a year from 2007 to 2013, compared with an average of 6.4 shootings annually from 2000 to 2006. In the past 13 years, 486 people have been killed in such shootings, with 366 of the deaths in the past seven years. In all, the study looked at 160 shootings since 2000.