user: Question: What is the average year of an entrant that had fewer than 6 points and a Maserati Straight-6 engine?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1951.0, 'Scuderia Milano', 'Maserati 4CLT/48', 'Maserati Straight-4', 0.0]
SQL:

assistant: SELECT AVG("Year") FROM "Table" WHERE "Points" < 6.0 AND "Engine" = 'Maserati Straight-6';