Last year we admitted 0 students from the waitlist. The year before that, we admitted 27 students from the waitlist, and the year before that we admitted 65 students. Please don't try to draw a trend line from 3 points - it's impossible to know what the yield will be this year.
Try to call them to follow up now! I just got off the waitlist last week - they are giving out waitlist slots RIGHT NOW. Based on this link below, at least one other person got in from WL.