Mean height of adult males, or entire population?
1 out of 25 adult males seems lower than I would have expected.
Male population.... average height in the US is around 5'9", and the standard deviation is around 2.5".
From what I've seen, that sounds about right. A true 6'3"+ tends to stick out.
EDIT: beaten by hulkotron. Seems the exact values vary depending on the source, but yeah basically 90-95% of the population are shorter than 6'3"