1-3:would make me scared.
3-6:still a little nervous, but know other people who only went to this many and matched.
7-9: doing pretty well.
10-15: I think that with 10 interviews, a candidate with any social ability should be able to match.
>15: You have blown too much $ on the interview trail.
I had 13, BTW. I had to turn down 1-2 because of date conflicts, but can't really remember that well.