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

### Instruction:
What is the average week that there was a game with less than 18,517 fans attending and occurred on November 21, 1954?

### Inputs:
table_name: table, columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']

### Response:
SELECT AVG Week FROM table WHERE Attendance < 18,517 AND Date = november 21, 1954