Question: How many drivers have participated in 30 or fewer races?
SQL: SELECT COUNT ( * )  FROM  ( SELECT T1.driverid  FROM drivers AS T1 JOIN results AS T2 ON T1.driverid  =  T2.driverid JOIN races AS T3 ON T2.raceid  =  T3.raceid GROUP BY T1.driverid HAVING count ( * )   < =   30 )