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: What are the different classes of races, and how many races correspond to each? | race : race_id , name , class , date , track_id | track : track_id , name , location , seating , year_opened | race.track_id = track.track_id | 

### Response:

select _ , count ( _ ) from _ group by _ | select class , count ( * ) from race group by class