Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE university ( affiliation VARCHAR, enrollment INTEGER )

### Question ###
Find the number of universities that have over a 20000 enrollment size for each affiliation type.

### Accurate SQL ###

SELECT COUNT(*), affiliation FROM university WHERE enrollment > 20000 GROUP BY affiliation