Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: Find the number of universities that have over a 20000 enrollment size for each affiliation type. | basketball_match : team_id , school_id , team_name , acc_regular_season , acc_percent , acc_home , acc_road , all_games , all_games_percent , all_home , all_road , all_neutral | university : school_id , school , location , founded , affiliation , enrollment , nickname , primary_conference | basketball_match.school_id = university.school_id | 

### Response:

select count ( _ ) , _ from _ where _ group by _ | select count ( * ) , affiliation from university where enrollment > 20000 group by affiliation