Database: books
Question: How many percent of orders in 2020 used international shipping?
SQL: SELECT CAST(SUM(CASE WHEN T2.method_name = 'International' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM cust_order AS T1 INNER JOIN shipping_method AS T2 ON T1.shipping_method_id = T2.method_id WHERE STRFTIME('%Y', T1.order_date) = '2020'