What is listed as the Date made with a Quantity made of 13?
CREATE TABLE table_68987 (
    "Class" text,
    "Type" text,
    "Fleet numbers" text,
    "Quantity made" real,
    "Manufacturer" text,
    "Date made" text,
    "Date withdrawn" text
)
SELECT "Date made" FROM table_68987 WHERE "Quantity made" = '13'
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 listed as the Date made with a Quantity made of 13? ### Input: CREATE TABLE table_68987 (
    "Class" text,
    "Type" text,
    "Fleet numbers" text,
    "Quantity made" real,
    "Manufacturer" text,
    "Date made" text,
    "Date withdrawn" text
) ### Response: SELECT "Date made" FROM table_68987 WHERE "Quantity made" = '13'