How many percent of Bluefish dishes are located at the center of the menu page?
percent = MULTIPLY(DIVIDE(SUM(xpos BETWEEN 0.25 AND 0.75 and ypos BETWEEN 0.25 AND 0.75), COUNT(id)), 1.0); Bluefish is a sub name of dish; located at the center of the menu page refers to xpos BETWEEN 0.25 AND 0.75 and ypos BETWEEN 0.25 AND 0.75;
SELECT CAST(SUM(CASE WHEN T2.xpos BETWEEN 0.25 AND 0.75 AND T2.ypos BETWEEN 0.25 AND 0.75 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T2.id) FROM Dish AS T1 INNER JOIN MenuItem AS T2 ON T1.id = T2.dish_id WHERE T1.name LIKE '%BLuefish%'