Database: cars
Question: Which country produced the highest number of cars? Calculate the annual average number of cars that the said country produced from the very start to the present.
SQL: SELECT T2.country, CAST(COUNT(T1.ID) AS REAL) / COUNT(DISTINCT T1.model_year) FROM production AS T1 INNER JOIN country AS T2 ON T1.country = T2.origin GROUP BY T2.country ORDER BY COUNT(T2.country) DESC LIMIT 1