What was the average crowd size at a home game that had a score of 14.15 (99)?
CREATE TABLE "round_20" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);
SELECT AVG("crowd") FROM "round_20" WHERE "home_team_score"='14.15 (99)';