CREATE TABLE table_71618 ("Year" FLOAT, "Entrant" CLOB, "Chassis" CLOB, "Engine" CLOB, "Points" FLOAT)

What is the year with a kurtis kraft 500a chassis?
SELECT SUM("Year") FROM table_71618 WHERE "Chassis" = 'kurtis kraft 500a'
SELECT SUM("Year") FROM "table_71618" WHERE "Chassis" = 'kurtis kraft 500a'