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

### Instruction:
What is the average win percentage of a season with a GB of 5?

### Inputs:
table_name: table, columns: ['Year', 'Record [a ]', 'Win %', 'League [b ]', 'Division [c ]', 'GB [d ]', 'Post-season record [e ]', 'Post-season win %', 'MLB affiliate [f ]']

### Response:
SELECT AVG Win % FROM table WHERE GB [d ] = 5