user: Question: When was Windy Hill used as a venue?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Melbourne', '15.9 (99)', 'Richmond', '17.14 (116)', 'MCG', 19567.0, '22 August 1981']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Venue" = 'Windy Hill';