Colleges continue to struggle to fill classes by May 1

“Around 450 U.S. colleges still have spots to fill in their incoming class past the traditional May 1 admissions decision deadline, according to data compiled annually by the National Association of College Admission Counseling (NACAC). That marks a continued increase over previous years in the number of colleges listed by NACAC as of May 1.” …

https://www.educationdive.com/news/colleges-continue-to-struggle-to-fill-classes-by-may-1/554831/

How has Pew reached this conclusion?