Question: Which ingredient appeared the most in recipes? Calculate its amount of appearance in percentage.
SQL: SELECT T1.name, CAST(COUNT(T2.ingredient_id) AS FLOAT) * 100 / ( SELECT COUNT(T2.ingredient_id) FROM Ingredient AS T1 INNER JOIN Quantity AS T2 ON T2.ingredient_id = T1.ingredient_id ) AS "percentage" FROM Ingredient AS T1 INNER JOIN Quantity AS T2 ON T2.ingredient_id = T1.ingredient_id GROUP BY T2.ingredient_id ORDER BY COUNT(T2.ingredient_id) DESC LIMIT 1