user: Question: What is the average crowd size for Richmond home games?
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', '10.14 (74)', 'Hawthorn', '11.18 (84)', 'Western Oval', 13789.0, '23 May 1981']
SQL:

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