CREATE TABLE table_57218 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

When did an away team have a score of 12.9 (81)?
SELECT "Date" FROM table_57218 WHERE "Away team score" = '12.9 (81)'
SELECT "Date" FROM "table_57218" WHERE "Away team score" = '12.9 (81)'