I was at a casting clinic a few years ago and the instructor (Bob Clouser) asked the group of around 25 people for a show of hands as to how far they could cast.
I didn't notice what the average was, but only 2 of us raised their hands at 80 feet.
After Bob stared me down for a while
he asked who could cast more than 80'.... no one raised their hands.
He went on to say that 80 feet is about as far as the average fly caster can expect reach in a fishing situation.