This is not statistically significant. There are 130,900 public schools in America. Roughly 130,880 of them have never been shot at. It sucks for the ones who have, but they are 0.015% of the total.

Your math isn't very good. Maybe at least make sure you are within an order of magnitude, next time, especially when it's so very Googlable.

You're saying 20 schools have experienced shootings, total, ever?

Nope. There have been 119 just in the first five months of this year. It's around 1,369 total since 1970.

https://www.washingtonpost.com/graphics/2018/local/school-sh... https://worldpopulationreview.com/state-rankings/school-shoo...

Nor is it even relevant.