What was the crowd when the home team had a score of 16.21 (117)?
CREATE TABLE "round_15" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);
SELECT "crowd" FROM "round_15" WHERE "home_team_score"='16.21 (117)';