Question: How many percent of Bluefish dishes are located at the center of the menu page?
SQL: 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%'