Database: formula_1
Question: For the drivers who took part in the race in 1983/7/16, what's their race completion rate?
SQL: SELECT CAST(COUNT(CASE WHEN T2.time IS NOT NULL THEN T2.driverId END) AS REAL) * 100 / COUNT(T2.driverId) FROM races AS T1 INNER JOIN results AS T2 ON T2.raceId = T1.raceId WHERE T1.date = '1983-07-16'