user: Question: How big was the crowd in game that featured the visiting team of North Melbourne?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Fitzroy', '19.18 (132)', 'Geelong', '9.11 (65)', 'Junction Oval', 17520.0, '16 June 1979']
SQL:

assistant: SELECT "Crowd" FROM "Table" WHERE "Away team" = 'North Melbourne';