user: Question: What is the average crowd size for games with North Melbourne as the away side?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Footscray', '8.16 (64)', 'North Melbourne', '7.11 (53)', 'Western Oval', 15000.0, '11 May 1929']
SQL:

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