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

### Instruction:
What is the total year of the winner who plays the halfback position with a % of points possible of 80.64%?

### Inputs:
table_name: table, columns: ['Year', 'Winner', 'School', 'Position', 'Points', '% of Points Possible']

### Response:
SELECT COUNT Year FROM table WHERE Position = halfback AND % of Points Possible = 80.64%