Vermonster-
Are those percentages for all bowhunters combined or just trad bowhunters?
If there is a 25% success rate for NBEF graduates, what percent of those successful are traditional bowhunters? Assuming 10% of those successful were traditional bowhunters, that would give you an overall traditional success rate of 2.5% for those who graduate NBEF. Of course, that doesn't take into account the actual number of traditional archers who graduated vs the number who were successful.
That is the problem with statistics, it just depends on how you do the math. Overall, looking at everyone's statistics and taking the average, an accurate number is probably somewhere between 2%-7% for traditional bowhunters.
It would be interesting to do a survey among this site comparing the success rate with years of experience, amount of practice, and time afield.