ok, some basic analysis I did. I looked up my old version of The Hidden Game of Football, and I found this date.
from 1982-1986, FG attempts from 20-29 yards were 89% successful.
this data is 20+ years old; given that we now know that extra points (= 20 yard FG's) are
96% successful, and kickers are much better now, I think it's fair to assume that that 89% figure is now up 5% higher: 94%. So if we know that 20 yarders are made at 96% ish, and we can guess that the average between 20-29 is 94%, I think a likely current distribution is something like this:
20 96.5%
21 96.0%
22 95.5%
23 95.0%
24 94.5%
25 94.0%
26 93.5%
27 93.0%
28 92.5%
29 92.0%
meaning going from 24% to 29% probably changes the kick from 94% to 92%
that analysis is far from perfect, but the #'s intuitively make sense.