What is the percentage of cars that was produced by Japan among those that have a sweep volume of no less than 30?
produced by Japan refers to country = 'Japan'; a sweep volume of no less than 30 refers to divide(displacement, cylinders) > 30; percentage = divide(count(ID where country = 'Japan'), count(ID)) * 100% where divide(displacement, cylinders) > 30
SELECT CAST(SUM(CASE WHEN T3.country = 'Japan' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM data AS T1 INNER JOIN production AS T2 ON T1.ID = T2.ID INNER JOIN country AS T3 ON T3.origin = T2.country WHERE T1.displacement / T1.cylinders > 30