Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_75 (year INTEGER, class VARCHAR, wins VARCHAR)
### Question:
Class of 500cc, and a Wins smaller than 0 had what average year?
### Answer:
SELECT AVG(year) FROM table_name_75 WHERE class = "500cc" AND wins < 0