What was the crowd size for the game where Footscray was the away team?
CREATE TABLE "round_19" (
  "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_19" WHERE "away_team"='footscray';