user: ### NOW ANSWER:
Question: How many years were G Tyres and Minardi M187 used?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Tyres', 'Points']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1985.0, 'Minardi Team SpA', 'Minardi M185', 'Motori Moderni Tipo 615-90 1.5 V6 t', 'P', 0.0]
SQL:

assistant: SELECT AVG("Year") FROM "Table" WHERE "Tyres" = 'G' AND "Chassis" = 'Minardi M187';