user: Question: What is Tony Stewart's average speed?
Columns: ['Year', 'Date', 'Driver', 'Team', 'Manufacturer', 'Laps', 'Miles (km)', 'Race Time', 'Average Speed (mph)', 'Report']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1960.0, 'October 16', 'Speedy Thompson', 'Wood Brothers Racing', 'Ford', '267', '400.5 (644.542)', '3:32:50', '112.905', 'Report']
SQL:

assistant: SELECT "Average Speed (mph)" FROM "Table" WHERE "Driver" = 'Tony Stewart';