how long did they produce singles ?
CREATE TABLE table_203_629 (
    id number,
    "year" number,
    "title" text,
    "lead vocalist" text,
    "aria chart position" number,
    "album" text
)
SELECT MAX("year") - MIN("year") FROM table_203_629
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: how long did they produce singles ? ### Input: CREATE TABLE table_203_629 (
    id number,
    "year" number,
    "title" text,
    "lead vocalist" text,
    "aria chart position" number,
    "album" text
) ### Response: SELECT MAX("year") - MIN("year") FROM table_203_629