user: Question: What is the average crowd of the 13.9 (87) Home Team Score?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Ground', 'Crowd', 'Date', 'Time']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Adelaide', '17.14 (116)', 'Collingwood', '9.8 (62)', 'Football Park', 20617.0, 'Friday 21 February 1997', '8:00 PM']
SQL:

assistant: SELECT AVG("Crowd") FROM "Table" WHERE "Home team score" = '13.9 (87)';