How many winners were there for stage 5?
CREATE TABLE "classification_leadership" (
  "stage" real,
  "winner" text,
  "general_classification" text,
  "mountains_classification" text,
  "sprint_classification" text,
  "young_rider_classification" text,
  "team_classification" text,
  "aggressive_rider" text
);
SELECT COUNT("winner") FROM "classification_leadership" WHERE "stage"=5;