user: Question: What was the earliest year for a car with 3 points and Cooper T20 chassis?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1952.0, 'Scuderia Franera', 'Frazer-Nash FN48', 'Bristol Straight-6', 3.0]
SQL:

assistant: SELECT MIN("Year") FROM "Table" WHERE "Points" = 3.0 AND "Chassis" = 'Cooper T20';