CREATE TABLE table_71424 ("Year" FLOAT, "Entrant" TEXT, "Chassis" TEXT, "Engine" TEXT, "Points" FLOAT)

What was the sum of the years, when the entrant was Scuderia Ferrari, and when the Chassis was Ferrari 312/66?
SELECT SUM("Year") FROM table_71424 WHERE "Entrant" = 'scuderia ferrari' AND "Chassis" = 'ferrari 312/66'
SELECT SUM("Year") FROM "table_71424" WHERE "Chassis" = 'ferrari 312/66' AND "Entrant" = 'scuderia ferrari'