user: Question: How many years had a formula of grand prix?
Columns: ['Year', 'Formula', 'Driver', 'Constructor', 'Location', 'Report']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1902.0, 'Grand Prix', 'Charles Jarrott', 'Panhard 70', 'Bastogne', 'Report']
SQL:

assistant: SELECT COUNT("Year") FROM "Table" WHERE "Formula" = 'grand prix';