Which Date has a Winning score of −15 (71-69-68-65=273)?
CREATE TABLE "european_tour_wins_7" (
  "date" text,
  "tournament" text,
  "winning_score" text,
  "margin_of_victory" text,
  "runner_up" text
);
SELECT "date" FROM "european_tour_wins_7" WHERE "winning_score"='−15 (71-69-68-65=273)';