user: Question: How many constructors had a grid of 13?
Columns: ['Pos', 'Grid', 'Car', 'Driver', 'Constructor', 'Manufacturer', 'Laps', 'Laps Led', 'Points']
Types: ['real', 'real', 'real', 'text', 'text', 'text', 'real', 'real', 'real']
Sample row: [1.0, 3.0, 42.0, 'Juan Pablo Montoya', 'Earnhardt Ganassi Racing', 'Chevrolet', 90.0, 74.0, 195.0]
SQL:

assistant: SELECT COUNT("Constructor") FROM "Table" WHERE "Grid" = 13.0;