How many orders were delivered in 2021?
delivered refers to status_value = 'Delivered'; in 2021 refers to status_date LIKE '2021%'
SELECT COUNT(*) FROM order_status AS T1 INNER JOIN order_history AS T2 ON T1.status_id = T2.status_id WHERE T1.status_value = 'Delivered' AND STRFTIME('%Y', T2.status_date) = '2021'