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.
the highest number of cars refers to max(country); annual average number = divide(count(ID), count(model_year))
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
database name:db_id cars
country table country Cols: origin dtype integer, country dtype text, 
price table price Cols: ID dtype integer, price dtype real, 
data table data Cols: ID dtype integer, mileage per gallon dtype real, number of cylinders dtype integer, displacement dtype real, horse power dtype integer, weight dtype integer, acceleration dtype real, model dtype integer, car name dtype text, 
production table production Cols: ID dtype integer, model year dtype integer, country dtype integer, 
