CREATE TABLE table_70315 ("Year" FLOAT, "Entrant" TEXT, "Chassis" TEXT, "Engine" TEXT, "Points" FLOAT)

Name the total number of years for chassis of ensign n175
SELECT COUNT("Year") FROM table_70315 WHERE "Chassis" = 'ensign n175'
SELECT COUNT("Year") FROM "table_70315" WHERE "Chassis" = 'ensign n175'