Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What year was the Competition of World Junior Championships with a 20th (qf) position?

### Inputs:
table_name: table, columns: ['Year', 'Competition', 'Venue', 'Position', 'Event', 'Notes']

### Response:
SELECT AVG Year FROM table WHERE Competition = world junior championships AND Position = 20th (qf)