user: Question: On what date did the away team score 12.9 (81)?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Richmond', '13.13 (91)', 'St Kilda', '7.11 (53)', 'Punt Road Oval', 20000.0, '13 July 1929']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Away team score" = '12.9 (81)';