Where can I find average GPA data by graduate year and college, and ideally by major too?

Question

I'm looking for a data source of average GPA results from each college in the US by graduate year. In an ideal world, an additional level of granularity would by by graduate major for a given college?

I'm thinking this is basically impossible to find, particularly for private schools, but any input would be appreciated.

I've found basically every other data point possible via the excellent collegescorecard.ed.gov