user: Question: What's the average crowd size when the Home team is 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: ['Hawthorn', '12.12 (84)', 'North Melbourne', '15.19 (109)', 'Glenferrie Oval', 5000.0, '26 August 1944']
SQL:

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