Database: superstore
Question: Calculate the percentage of ordered office supplies products in the central and the south superstore.
SQL: SELECT CAST(SUM(CASE  WHEN T3.Category = 'Office Supplies' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T3.Category) FROM people AS T1 INNER JOIN central_superstore AS T2 ON T1.`Customer ID` = T2.`Customer ID` INNER JOIN product AS T3 ON T3.`Product ID` = T2.`Product ID`