user: Question: What is the average laps for the grid smaller than 21 for Renzo Zorzi?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Niki Lauda', 'Ferrari', 40.0, '1:45:16.78', 2.0]
SQL:

assistant: SELECT AVG("Laps") FROM "Table" WHERE "Grid" < 21.0 AND "Driver" = 'Renzo Zorzi';