A lot of gunshot wound survival stats aren't relevant to selection of defensive ammunition. They include a lot of accidental shootings, which are often wounds to the extremities that don't damage the great vessels and are not life-threatening, or necessarily even incapacitating.
In any case, we're not looking for lethality, we're looking for swift cessation of action. Often, people who were instantly "stopped" make the survivors' list. And, of course, trauma care is getting better and better all the time.
Sorry I couldn't offer a more specific answer,