Why aren't we as concerned by the largest percentage.....56%....from suicide?
Because politicians are amazingly flexible. A suicide shooter - generally - only harms himself (it's usually a dude) as far as DEATH or injury is concerned (yes, there are exceptions).
And for the record, I seriously doubt "mass shootings" (a randomly defined term like, you know, "assault weapon") have risen nearly as much as is assumed. I think they've gone up but not nearly as much as the average person would presume.
Why do I say this?
Because I read old newspapers and guess what I've discovered by reading?
1) there were a ton of what today would be called "mass shootings" that were local, back in the days before CNN Headline News (1982) followed by the Net followed by text messaging, along with the ubiquitous cameras (note: there has also been a concurrent decline in the number of known and active 'serial killers').
2) there were also A BUNCH of "healthy athletes" who "died suddenly" on playing fields, too, contra the anti-vax imbeciles.
But I've also learned this fact: show these to people, show them newspapers from the 1960s (and earlier) with local stories about a healthy athlete collapsing and dying on a field - and they pivot from "this never happened before" (uh, yes it did, you just didn't hear about it) "what do you think this proves" (uh, it proves you're mistaken when you say "this never happened before" and henceforth, you're just lying).