user: Question: When did NSWRFL has a score of 8-21?
Columns: ['Year', 'Opponent', 'Competition', 'Score', 'Venue', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1951.0, 'South Sydney Rabbitohs', 'NSWRFL', '14-42', 'Sydney Sports Ground', 28505.0]
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Competition" = 'NSWRFL' AND "Score" = '8-21';