user: Question: What is the number of pole position with a round of 15?
Columns: ['Round', 'Grand Prix', 'Date', 'Location', 'Pole Position', 'Fastest Lap', 'Winning Driver', 'Winning Constructor', 'Report']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'United States Grand Prix', '11 March', 'Phoenix', 'Gerhard Berger', 'Gerhard Berger', 'Ayrton Senna', 'McLaren - Honda', 'Report']
SQL:

assistant: SELECT COUNT("Pole Position") FROM "Table" WHERE "Round" = 15.0;