Write SQL query to solve given problem: What is the average unit profit for wholesalers of canned beers?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT AVG(T2.CurrentRetailPrice - T2.WholesaleCost) FROM rootbeer AS T1 INNER JOIN rootbeerbrand AS T2 ON T1.BrandID = T2.BrandID WHERE T1.ContainerType = 'Can'