Among the businesses with a category of Food, what is the percentage of the business with greater than 3 stars?
category of food refers to category_name = 'Food'; calculation = DIVIDE(COUNT(stars > 3), SUM(stars))
SELECT CAST(SUM(CASE WHEN T1.stars > 3 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.stars) FROM Business AS T1 INNER JOIN Business_Categories AS T2 ON T1.business_id = T2.business_id INNER JOIN Categories AS T3 ON T2.category_id = T3.category_id WHERE T3.category_name = 'Food'