SELECT AVG("Year") FROM table_14475 WHERE "Engine" = 'cosworth ca2006 2.4 v8 4 series'
What year was the cosworth ca2006 2.4 v8 4 series used?
CREATE TABLE table_14475 (
    "Year" real,
    "Entrant" text,
    "Chassis" text,
    "Engine" text,
    "Points" text
)