For the orders of Customer "WHITC", what is the percentage of the orders were fulfilled with shipper company "United Package"?
Customer "WHITC" refers to CustomerID = 'WHITC'; shipper company "United Package" refers to CompanyName = 'United Package'; percentage = divide(count(ShipperID where CompanyName = 'United Package') , count(ShipperID)) * 100%
SELECT CAST(COUNT(CASE WHEN T2.CompanyName = 'United Package' THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(T1.OrderID) FROM Orders AS T1 INNER JOIN Shippers AS T2 ON T1.ShipVia = T2.ShipperID WHERE T1.CustomerID = 'WHITC'