Three. The first year it was early, I BARELY had the pre reqs covered, wasn't going to graduate yet and didn't even get an interview. The second year I had a bunch of interviews and was waitlisted all over the place. Never got called. Last year I refined my process, narrowed down schoosl. Had interviews, accepted here, waitlisted at MN. Got called off the wailist at MN but still chose here. I had really good stats, thousand and thousands of hours of varied experience and thought I would crush interviews since I am such a people person.
Don't try to make sense of the process. It's like trying to find the answer to a math problem when we don't even have the equation. I think that (at least especially at WSU) each student fills a niche. And the makeup of each class is different from year to year so those niches change. Don't give up.