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

### Instruction:
Which Week has an Opponent of baltimore colts, and an Attendance smaller than 55,137?

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

### Response:
SELECT AVG Week FROM table WHERE Opponent = baltimore colts AND Attendance < 55,137