Database: formula_1
Question: What is the average time in seconds of champion for each year, before year 1975?
SQL: WITH time_in_seconds AS ( SELECT T2.year, T2.raceId, T1.positionOrder, CASE WHEN T1.positionOrder = 1 THEN (CAST(SUBSTR(T1.time, 1, 1) AS REAL) * 3600) + (CAST(SUBSTR(T1.time, 3, 2) AS REAL) * 60) + CAST(SUBSTR(T1.time, 6,2) AS REAL )   + CAST(SUBSTR(T1.time, 9) AS REAL)/1000 ELSE 0 END AS time_seconds FROM results AS T1 INNER JOIN races AS T2 ON T1.raceId = T2.raceId WHERE T1.time IS NOT NULL ), champion_time AS ( SELECT year, raceId, time_seconds FROM time_in_seconds WHERE positionOrder = 1 ) SELECT year, AVG(time_seconds) FROM champion_time WHERE year < 1975 GROUP BY year HAVING AVG(time_seconds) IS NOT NULL