Database: retail_world
Question: How many percent more orders were fulfilled with shipper company "United Package" than with "Speedy Express"?
SQL: SELECT CAST((COUNT(CASE WHEN T2.CompanyName = 'United Package' THEN 1 ELSE NULL END) - COUNT(CASE WHEN T2.CompanyName = 'Speedy Express' THEN 1 ELSE NULL END)) AS REAL) * 100 / COUNT(CASE WHEN T2.CompanyName = 'Speedy Express' THEN 1 ELSE NULL END) FROM Orders AS T1 INNER JOIN Shippers AS T2 ON T1.ShipVia = T2.ShipperID