user: Question: How many winning drivers were the for the rnd equalling 5?
Columns: ['Rnd', 'Race Name', 'Circuit', 'City/Location', 'Date', 'Pole position', 'Winning driver', 'Winning team', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'Checker Autoworks 200', 'Phoenix International Raceway', 'Phoenix, Arizona', 'April 9', 'Rick Mears', 'Rick Mears', 'Team Penske', 'Report']
SQL:

assistant: SELECT COUNT("Winning driver") FROM "Table" WHERE "Rnd" = '5';