Well figuring they claim a whitetail can life 20 years, I'd say 1%...if that. Many may die of natural causes but not through a realistic life span. I'd bet there are many, let's say bucks that make 6 years old and die over a winter etc...but they are barely an old deer yet. A deer isn't even considered mature until he's in his 5th year, (is that right?) and the percentage that see 5 years are low.