Easy, their numbers were inaccurate which obviously they were lol.
You should realize that predicting something like a death rate is literally impossible.
At best you can get a ballpark figure but many things can throw that off.
Have you ever taken a statistics class?
Yes. Obviously you haven't. Yes you can predict the number of deaths in a population. It's very easy. What evidence do you have that the numbers I posted were wrong? Do you have another figure you believe is more accurate? Go ahead and post it. Yeah, didn't think so.

