Great point you have there, indeed. Well, yes. If from the murder total you substract those that didn't involve previous planning, the rest are mostly, planned crimes. Uncanny logic you got there, buddy.
Read the newspapers, watch the news. All the stats you should need are there. It's not everyday a DC sniper pops up, fortunately.
Interestingly enough, those were different times and for starters, you couldn't buy an assault rifle at the grocery.