18/20 = 90%
The results are very instructive, because there are enough questions and a quite large number of contestants. You have a peak at 25%, that just happens to be the average mark you get if you answer randomly, since there are 4 possible answers for each question. You have some kind of bell curve around 25%, meaning that those who are over it were a bit lucky (or maybe know 1 or 2 things about Deb, but really not much), and those under were a bit unlucky.
Then, from 70% on, you have again a large number of contestants who cannot possibly get theses marks only on sheer luck : these guys are the fans, that know Deb. The average for them is 85,27%, which is pretty good because there are a few not-so-obvious questions IMO.
Out of the 95 contestants, 37 are obviously fans and a large part of the 58 aren't (the 5 "fringe" contestants with 65, 60 or 55% could be non-hardcore fans (but still fans) with a few mistakes, or possibly very lucky guys, there's no way to know) ; they're just passers-by, but probably know Deb's name or remember her at least a little bit or else they wouldn't even have taken the quizz. It's difficult to extrapolate from these numbers because there are not representative of the population : since you have posted the link on Deb's fansites (at least on Dariusz' one), there will be a larger number of Deb fans taking the quizz than average.
What I don't know is if 95 contestants is a good score compared to other quizzes. That kind of comparison could be helpful to compare Deb's popularity to other singers'. I took a NKOTB quizz (band of Deb's era, with similar success) just to check the number of contestants and it was 134, so not very far from Deb. That tends to show that Deb is no more or no less "forgotten" than NKOTB. Of course you'd need a larger number of quizzes and contestants to really compare.
