Database: formula_1
Question: Among the drivers that finished the race in the 2008 Chinese Grand Prix, how many of them have participated in Formula_1 races?
SQL: SELECT COUNT(*) FROM ( SELECT T1.driverId FROM results AS T1 INNER JOIN races AS T2 on T1.raceId = T2.raceId WHERE T2.name = 'Chinese Grand Prix' AND T2.year = 2008 AND T1.time IS NOT NULL GROUP BY T1.driverId HAVING COUNT(T2.raceId) > 0 )