user: ### NOW ANSWER:
Question: How many years was Ensign N180B a Chassis with 4 points?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1979.0, 'Team Ensign', 'Ensign N179', 'Cosworth V8', 0.0]
SQL:

assistant: SELECT SUM("Year") FROM "Table" WHERE "Points" = 4.0 AND "Chassis" = 'Ensign N180B';