In 2020, what were the total orders of all stores in Maricopa County?
total orders refer to COUNT(OrderNumber); 2020 refers to SUBSTR(OrderDate, -2) = '20';
SELECT SUM(CASE WHEN T2.County = 'Maricopa County' AND OrderDate LIKE '%/%/20' THEN 1 ELSE 0 END) FROM `Sales Orders` AS T1 INNER JOIN `Store Locations` AS T2 ON T2.StoreID = T1._StoreID