user: Question: What is the Winning score when the To par was −21?
Columns: ['Date', 'Tournament', 'Winning score', 'To par', 'Margin of victory', 'Runner(s)-up']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1 Aug 2004', 'Scandinavian Masters by Carlsberg', '69-65-69-69=272', '−16', '5 strokes', 'Peter Hanson']
SQL:

assistant: SELECT "Winning score" FROM "Table" WHERE "To par" = '−21';