sub 2:10 According to the the all time list of us marathons about 15 runners have gone sub 2:10 but only 3 of them are still running by my reckoning. This is a serious pro time.
sub 2:20 Cant find the year list of times but i would guess that some where in the neighborhood of 50 runners that could do this if they really went for it. Still a pretty big time.
sub 2:30 Now you're getting in to the range of guys whom are not even pro runners maybe former college guys who are still in great shape and trying to break in to the sub 2:20 group. My guess is about there are about 200-300 of these guys out there.
sub 2:40 There are lots and lot of these guys the first guy in this group at last year Chicago marathon was in 185th place to give you an idea. There are hundreds maybe even thousands of them, although you still have to be in decent shape to run this time.
sub 2:50 alot who cares its like asking how many guys can break 19 min in the 5k.
sub 3:00 if you are worried about cracking 3 you are just a fun runner who is trying to get in to marathon running. Still cool for them but not really worth talking about time. There are thousands.