What year was the aircraft retired when it was replaced by 737-300s?
CREATE TABLE table_60831 (
    "Aircraft" text,
    "Introduced" real,
    "Retired" text,
    "Seating" text,
    "Notes" text
)
SELECT "Retired" FROM table_60831 WHERE "Notes" = 'replaced by 737-300s'
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 year was the aircraft retired when it was replaced by 737-300s? ### Input: CREATE TABLE table_60831 (
    "Aircraft" text,
    "Introduced" real,
    "Retired" text,
    "Seating" text,
    "Notes" text
) ### Response: SELECT "Retired" FROM table_60831 WHERE "Notes" = 'replaced by 737-300s'