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

### Instruction:
What is the average goals against average for those playing more than 78 games?

### Inputs:
table_name: table, columns: ['Player', 'Years', 'Games played', 'Goals allowed', 'Goals against average']

### Response:
SELECT AVG Goals against average FROM table WHERE Games played > 78