Write SQL query to solve given problem: What percentage of orders were placed by customers in Madrid city in 1996?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT CAST(COUNT(CASE WHEN T1.City = 'Madrid' THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(T1.City) FROM Customers AS T1 INNER JOIN Orders AS T2 ON T1.CustomerID = T2.CustomerID WHERE STRFTIME('%Y', T2.OrderDate) = 1996