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_18 (year INTEGER, competition VARCHAR, position VARCHAR)
### Question:
What year was the Competition of World Junior Championships with a 20th (qf) position?
### Answer:
SELECT AVG(year) FROM table_name_18 WHERE competition = "world junior championships" AND position = "20th (qf)"