In this context, simply killing other humans, or any violence, is not equivalent to crime. Crime is dependent upon a collective interpretation of any act, not necessarily whether it's objectively destructive. A tribe may decide to wage war upon neighbors, sacrifice virgins, or what have you, but they do so under the impression that it's perceived to be in their coaligned interest.
This is relevant because the metric we're measuring now is exactly that: crime, not violence. WWIII could break out tomorrow, billions could die, and crime could still go down.
This is relevant because the metric we're measuring now is exactly that: crime, not violence. WWIII could break out tomorrow, billions could die, and crime could still go down.