What is the release year of the game that gained 350000 sales in North America?
gained 350000 sales refers to num_sales = 3.5; in North America refers to region_name = 'North America'
SELECT T3.release_year FROM region AS T1 INNER JOIN region_sales AS T2 ON T1.id = T2.region_id INNER JOIN game_platform AS T3 ON T2.game_platform_id = T3.id WHERE T2.num_sales * 100000 = 350000 AND T1.region_name = 'North America'