user: Question: What is the lowest grid that has over 67 laps with Stefan Bellof driving?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Alain Prost', 'McLaren - TAG', 71.0, '1:37:21.468', 1.0]
SQL:

assistant: SELECT MIN("Grid") FROM "Table" WHERE "Laps" > 67.0 AND "Driver" = 'Stefan Bellof';