About 20k students take the AP Computer Science exam each year, split 14k for the A-level and 6k for the AB-level. I was going to make some argument that the AP students are all aiming for top schools, but the numbers seem to say otherwise. At least, 14k sounds like a lot.
Wow, that is old. I looked up stats from the collegeboard website. I guess they haven't updated. Or maybe Google led me to an old page they haven't removed.