You can look up some stats on College Navigator, such as percentage of students with Pell grants (approximates students from the lower half of parental income) and percentage of students getting any grants or scholarships (the other side of that is full pay students, who must come from top ~4% income parents to be able to afford private college list price).
For example:
https://nces.ed.gov/collegenavigator/?q=trinity&s=all&id=130590#finaid
Trinity has 51% receiving grants or scholarships (so 49% full pay), with 11% receiving Pell grants.