user: Question: What is the sum of points in 1991, for Footwork A11C chassis?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1986.0, 'Osella Squadra Corse', 'Osella FA1G', 'Alfa Romeo V8', 0.0]
SQL:

assistant: SELECT SUM("Points") FROM "Table" WHERE "Year" = 1991.0 AND "Chassis" = 'Footwork A11C';