user: Question: What is the average year for a Merzario A2 chassis?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1972.0, 'Scuderia Ferrari', 'Ferrari 312B2', 'Ferrari Flat-12', 1.0]
SQL:

assistant: SELECT AVG("Year") FROM "Table" WHERE "Chassis" = 'Merzario A2';