SELECT AVG(year) FROM table_name_49 WHERE quantity = 10 AND gwr_numbers = "409, 290, 315, 317–321, 324, 333"
Berapa tahun rata -rata yang memiliki jumlah 10, dan jumlah GWR 409, 290, 315, 317-321, 324, 333?
CREATE TABLE table_name_49 (year INTEGER, quantity VARCHAR, gwr_numbers VARCHAR)