What is the average crowd size for Brunswick street oval?
CREATE TABLE "round_1" (
  "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_1" WHERE "venue"='brunswick street oval';