Why does Washu accept 0 waitlisted student every two years?

So I was looking at Washu Common Data Set https://wustl.edu/about/compliance-policies/registrar/student-consumer-information/ and I noticed that between each year that WashU accepted waitlisted students, they accepted 0 waitlisted students.

For example:

2015-2016: 129 waitlist accepted
2014-2015: 0
2013-2014: 80
2012-2013: 0
2011-2012: 152
2010-2011: 0

What’s up with that?

so basically this coming year no ones gonna come off the waitlist? oh boy… it might be that they only report their data set biannually?