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

### Instruction:
What average week number had the Chicago bears as the opponent?

### Inputs:
table_name: table, columns: ['Week', 'Date', 'Opponent', 'Game Site', 'Final Score', 'Record', 'TV Time', 'Attendance']

### Response:
SELECT AVG Week FROM table WHERE Opponent = chicago bears