Kate asked this morning about when mass shootings really took off.
I found a dataset compiled by Mother Jones magazine, and available here.
It's not too hard to turn that dataset into some charts.
Here's the frequency of mass shootings (as Mother Jones defines them), from 1982 through 2017:
Total people injured per year:
Victims (number killed plus number injured):
Here's all four measures in a single chart:
That one is dominated by the number of victims, because the number of injured is so much higher in 2017 than in any previous year, so I made another where each of the four indicators is "normalized" so that its level in 2017 is 100, and levels in previous years are scaled to be the appropriate relative size:
So in that sense the first chart, on frequencies, is the most revealing, and it shows an uneven but clear trend toward greater frequency.