Which Date has a Winning score of –14 (66-64-68-68=266)?
CREATE TABLE "pga_tour_wins_15" (
  "date" text,
  "tournament" text,
  "winning_score" text,
  "margin_of_victory" text,
  "runner_s_up" text
);
SELECT "date" FROM "pga_tour_wins_15" WHERE "winning_score"='–14 (66-64-68-68=266)';