64y.o. gunman very rare—Las Vegas shooting

The Las Vegas shooter (I won't say his name) was 64, which is an outlier. Last time I updated in 2015, only 2 of the 70 shooters were over age 60 (aged 64 &66), near the bottom in terms of victims.

This is all based on Mother Jones data on: "US Mass Shootings, 1982-2017," which I analyzed various ways. They no longer seem to list age, but I kept their data from when they did.

I was shocked to find 2 distinct age clusters: 1) post adolescent (as expected), but 2) LARGEST group, 40% "40ish" (ages 39-51). Few over 51.