CREATE TABLE table_13831 ("Date" FLOAT, "Ships sunk  ( Pola ) " TEXT, "Tonnage" TEXT, "U-boats destroyed  ( KuK ) " TEXT, "U-boats destroyed  ( Pola ) " TEXT)

What is listed as the average Date that has U-boats destroyed (KuK) of 2 with Tonnage of 1,514,050?
SELECT AVG("Date") FROM table_13831 WHERE "U-boats destroyed (KuK)" = '2' AND "Tonnage" = '1,514,050'
SELECT AVG("Date") FROM "table_13831" WHERE "Tonnage" = '1,514,050' AND "U-boats destroyed (KuK)" = '2'