SELECT AVG("Crowd") FROM table_54512 WHERE "Away team" = 'fitzroy'
What was the attendance when Fitzroy played as the away team?
CREATE TABLE table_54512 (
    "Home team" text,
    "Home team score" text,
    "Away team" text,
    "Away team score" text,
    "Venue" text,
    "Crowd" real,
    "Date" text
)