Vox has a discussion of the airliner hijackings we used to have in the US (and elsewhere).
I remember the time, didn't remember we reached 130 in 1968-72, but a lot. It's part of the fact that that period was also more violent: deaths due to terrorism were higher before 9/11 than after. The discussion touches on the idea that publicity spurred the hijackings, making them in some respects similar to today's mass shootings. You get a nut who wants attention, in 1970 he hijacked a plane, in 2016 he shoots a few people.