user: Question: In what year did a car have a Yamaha V12 engine and a Brabham BT60Y chassis
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Pts.']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1991.0, 'Motor Racing Developments Ltd', 'Brabham BT59Y', 'Yamaha V12', 1.0]
SQL:

assistant: SELECT "Year" FROM "Table" WHERE "Engine" = 'Yamaha V12' AND "Chassis" = 'Brabham BT60Y';