What is the ratio of game sales between North America and Japan?
ratio = DIVIDE(SUM(num_sales WHERE region_name = 'North America'), SUM(num_sales WHERE region_name = 'Japan')); North America refers to region_name = 'North America'; Japan refers to region_name = 'Japan';
SELECT SUM(CASE WHEN T2.region_name = 'North America' THEN T1.num_sales ELSE 0 END) / SUM(CASE WHEN T2.region_name = 'Japan' THEN T1.num_sales ELSE 0 END) FROM region_sales AS T1 INNER JOIN region AS T2 ON T1.region_id = T2.id