CREATE TABLE table_34805 ("Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "Margin of victory" TEXT, "Runner-up" TEXT)

Which Date has a Winning score of 15 (71-69-68-65=273)?
SELECT "Date" FROM table_34805 WHERE "Winning score" = '−15 (71-69-68-65=273)'
SELECT "Date" FROM "table_34805" WHERE "Winning score" = '−15 (71-69-68-65=273)'