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

### Instruction:
What was the attendance on 21 August 2004?

### Inputs:
table_name: table, columns: ['Date', 'Opponents', 'Result F–A', 'Attendance', 'League position']

### Response:
SELECT SUM Attendance FROM table WHERE Date = 21 august 2004