[Pearls Before Swine]

According to an extensive survey in the New York Times a few years ago, about half of rampage killings are committed by mentally ill people, a much higher percentage than the roughly five percent that commit all murders.

Can someone help me understand the last part of this sentence. Does this article claim that 5% of people are murderers? Or that 5% of murders are rampage murders of which 50% are committed by the mentally ill?

[stayathomemom]

I think it means that 5% of murders are committed by mentally ill people, while about 50% of rampage murders are committed by the mentally ill.

[browardchad]

Does this article claim that 5% of people are murderers? Or that 5% of murders are rampage murders of which 50% are committed by the mentally ill?

It's a confusing sentence, but since the 5% cannot possibly refer to the percentage of killers in the population, I assume he's saying that although only 5% of killers are judged mentally ill, half of all rampage killings are done by those judged mentally ill.