What is the total number of quantity when the introductory year was 1984?
CREATE TABLE table_35513 (
    "Manufacturer" text,
    "Model" text,
    "Quantity" real,
    "Introduced" real,
    "Retired" real
)
SELECT SUM("Quantity") FROM table_35513 WHERE "Introduced" = '1984'
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 total number of quantity when the introductory year was 1984? ### Input: CREATE TABLE table_35513 (
    "Manufacturer" text,
    "Model" text,
    "Quantity" real,
    "Introduced" real,
    "Retired" real
) ### Response: SELECT SUM("Quantity") FROM table_35513 WHERE "Introduced" = '1984'