CREATE TABLE table_57312 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

What is the average crowd size for Brunswick street oval?
SELECT AVG("Crowd") FROM table_57312 WHERE "Venue" = 'brunswick street oval'
SELECT AVG("Crowd") FROM "table_57312" WHERE "Venue" = 'brunswick street oval'