I've taken a 5-school moving average by rank here to make the graph more readable. By rank 11, we're at an acceptance rate of about 20%. By rank 21, we're above 30%. In the low- to mid-30s, we cross 40% and then 50%. There are plenty of well regarded schools in those ranks.
If you just measure selectivity by the percent of applicants rejected, the folks at WeGame U can find all sorts of ways to artificially boost the numbers in their applicant pool.
The statistic that I think would reveal the most about college selectivity would be the median SAT scores for the applicants who are rejected. If the school is routinely rejecting students with SAT's of around 700 (per section of the SAT), you know they are selective. On the other hand, if the median SAT score for rejected applicants is 520, you know that they are dealing with a mediocre applicant pool.