The history of the weapons is admittedly fascinating, but is there any data to suggest that mass killers "use" AR-15 and AK-47 more than the general population

The history of the weapons is admittedly fascinating, but is there any data to suggest that mass killers "use" AR-15 and AK-47 more than the general population or various military personel "uses" them. Every day people use Knives™ and Fists™ to carry out violent acts too. In the context of this discussion, it would be more interesting to know which one is winning out over time over the other family of weapons.