How common is androgenetic alopecia ( common hairloss )  in Caucasian men

There are not any  extensive research or clinical studies to clarify how common androgentic alopecia affects.
Casual watching suggests that the frequency in the Caucasian population is really high.
Many dermatologists  suggest that androgenetic alopecia can begin as soon as in the teenage years for some white men and the rate in elderly male Caucasians is almost 100%.

Anyway, this picture may be on the high side.  classifying,Examing and recording androgentic Alopecia is a  subjective method and by the time that some dermatologists register even the slightest hair loss others ( most of them ) ignore it as not being due to be androgenetic alopecia.
Androgenetic alopecia is inform that it affect between 60 and 70% of  men and around 50% of women.
A generic rule is that by 30 years , 30% have androgenetic alopecia. For men in their forties, 40% have alopecia and so on till at the age of 80 , nine of every 10 have androgenetic alopecia at some level .
It is important to know the fact about hair loss on and talk with another person ( for example in a hair loss forum ) if the hair loss is affecting the person life .