user: Question: What is the average grid for Jo Siffert?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Jackie Stewart', 'Matra - Ford', 80.0, '1:50:39.1', 4.0]
SQL:

assistant: SELECT AVG("Grid") FROM "Table" WHERE "Driver" = 'Jo Siffert';