What was the crowd size when the visiting team scored 23.18 (156)?
CREATE TABLE "round_9" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);
SELECT COUNT("crowd") FROM "round_9" WHERE "away_team_score"='23.18 (156)';