No one is trying to optimize it for. They're using it as a crude barometer for just how bad it is. We know about how many people die on average for any given p

No one is trying to optimize it for. They're using it as a crude barometer for just how bad it is. We know about how many people die on average for any given period. We expect it to be in a range. When it is wildly outside of that range, then there's something going on.