So you see these top med schools (top 30 lets say) with average GPA's being 3.7-3.9, but they accept maybe 2 or 3 percent of all applicants. How can that be?
There are a lot of qualified applicants. Especially at top med schools, which typically have a more self-selected pool of applicants (i.e. a person with a 2.5 isn't going to be applying to Harvard). You really can't fully appreciate how many qualified applicants there are until you're sitting on the other side of the table.
How many people with a 3.7 3.8 3.9 get rejected?
Many, if there are concerns that warrant rejection. More likely, they get waitlisted and end up going elsewhere.
Is it just that not many people with a high GPA apply? for instance do like 80 % of the applicants have a 3.5 or below a 3.6?
I believe the average GPA of a matriculating medical student is still hovering in the 3.6 vicinity. So not 80%.
I have an above average GPA but what does that mean? Could I still be rejected easily?
It means you worked hard in school and got mostly A's. That gives medical schools confidence that you can also excel academically in medical school. That's just one piece of the puzzle.
Yes you could still be rejected. MCAT score, lack of clinical exposure, bad LORs, extremely poor writing/essays, poor interview skills, professionalism concerns...all reasons people can be rejected. There are many factors that go into an admissions decision, and I've seen each and every one of these things be the downfall of someone with a 4.0.
Grades and numbers are not the be-all-end-all. Everyone is shocked when a 4.0/40 applicant doesn't do well in an application cycle, but it's really not that shocking and there's usually a reasonable explanation for it.