Database: regional_sales
Question: From 2018 to 2020, which year did the George Lewis group have the highest number of orders?
SQL: SELECT SUBSTR(T1.OrderDate, -2, 2) FROM `Sales Orders` AS T1 INNER JOIN `Sales Team` AS T2 ON T2.SalesTeamID = T1._SalesTeamID WHERE T2.`Sales Team` = 'George Lewis' GROUP BY SUBSTR(T1.OrderDate, -2, 2) ORDER BY COUNT(T1.OrderNumber) DESC LIMIT 1