What is the largest 6-car-sets for fiscal year 1968?
CREATE TABLE table_2020 (
    "Fiscal year" real,
    "2-car sets" real,
    "4-car sets" real,
    "6-car sets" real,
    "8-car sets" real,
    "Total vehicles" real
)
SELECT MAX("6-car sets") FROM table_2020 WHERE "Fiscal year" = '1968'
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 largest 6-car-sets for fiscal year 1968? ### Input: CREATE TABLE table_2020 (
    "Fiscal year" real,
    "2-car sets" real,
    "4-car sets" real,
    "6-car sets" real,
    "8-car sets" real,
    "Total vehicles" real
) ### Response: SELECT MAX("6-car sets") FROM table_2020 WHERE "Fiscal year" = '1968'