The UC Information Center has a large amount of data including admission for freshman by high school and UC campus. It's interactive so enter your high school to view statistics about the number of students admitted by ethnicity and GPA including average applied, admitted, and enrolled GPA, It also includes transfer student data. https://www.universityofcalifornia.edu/about-us/information-center/admissions-source-school.
Here is an admissions summary. https://www.universityofcalifornia.edu/about-us/information-center/freshman-admissions-summary