Waitlist data sometimes is published on the Common Dataset (CDS).
This is from last year:
Number of qualified applicants offered a place on waiting list: 9983
Number accepting a place on the waiting list: 5707
Number of wait-listed students admitted: 4097
Is your waiting list ranked? No
UCSC takes very few applicants off the waitlist so last year was an exception. It doesn’t specify if the # of Freshman vs # of Transfers.