I would say of the general runner population, 97% of MEN do pushups incorrectly. As another poster said, if someone put their fist under your chest, you should touch it and come all the way up with straight back/butt/legs. This is actually suprisingly hard.
I was on an XC team that took weights pretty seriously and very few of them could accomplish these standards
I have been to the law enforcement academy as well and can say that out of my graduating class of of about 80, the average amount was around 35-40 max out. This was for (somewhat) fit police officers. Only 2 Officers got over 100 and only about 10 got over 50.
My wife cant do but maybe 3 according to these standards...but shes very weak. When we started training weights for the first time 10 weeks ago, she couldnt do 10 "girl" pushups