CREATE TABLE table_name_13 (date INTEGER, u_boats_destroyed__kuk_ VARCHAR(255), tonnage VARCHAR(255))
What is listed as the average Date that has U-boats destroyed (KuK) of 2 with Tonnage of 1,514,050?
    
SQL: SELECT AVG(date) FROM table_name_13 WHERE u_boats_destroyed__kuk_ = "2" AND tonnage = "1,514,050"