Spree killings are anyway only a tiny proportion of gun deaths. There are about 30,000 gun deaths a year in the U.S.A., two-thirds of them suicides. Of the ten thousand or so that aren't suicides, spree killings are a fraction of one percent. If you add up the spree killings for 2015, for example, there were 3 in Chapel Hill in February, 9 in Charleston in June, 2 in Lafayette in July, and 14 in San Bernadino in December; total 28. Out of 30,000.Round it to thirty, and you've got an easy figure: one in a thousand.