how many Curtiss XBTC aircraft are retired?
CREATE TABLE table_13605170_2 (
    retired VARCHAR,
    aircraft_type VARCHAR
)
SELECT COUNT(retired) FROM table_13605170_2 WHERE aircraft_type = "Curtiss XBTC"
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 many Curtiss XBTC aircraft are retired? ### Input: CREATE TABLE table_13605170_2 (
    retired VARCHAR,
    aircraft_type VARCHAR
) ### Response: SELECT COUNT(retired) FROM table_13605170_2 WHERE aircraft_type = "Curtiss XBTC"