What is the average end year of the player from swe and a summer transfer window?
CREATE TABLE table_name_81 (
    ends INTEGER,
    nat VARCHAR,
    transfer_window VARCHAR
)
SELECT AVG(ends) FROM table_name_81 WHERE nat = "swe" AND transfer_window = "summer"
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 average end year of the player from swe and a summer transfer window? ### Input: CREATE TABLE table_name_81 (
    ends INTEGER,
    nat VARCHAR,
    transfer_window VARCHAR
) ### Response: SELECT AVG(ends) FROM table_name_81 WHERE nat = "swe" AND transfer_window = "summer"