What is the year with a kurtis kraft 500a chassis?
CREATE TABLE table_71618 (
    "Year" real,
    "Entrant" text,
    "Chassis" text,
    "Engine" text,
    "Points" real
)
SELECT SUM("Year") FROM table_71618 WHERE "Chassis" = 'kurtis kraft 500a'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the year with a kurtis kraft 500a chassis? ### Input: CREATE TABLE table_71618 (
    "Year" real,
    "Entrant" text,
    "Chassis" text,
    "Engine" text,
    "Points" real
) ### Response: SELECT SUM("Year") FROM table_71618 WHERE "Chassis" = 'kurtis kraft 500a'