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

### Instruction:
For how many years combined were Frank Gifford and Dan Dierdorf color commentators?

### Inputs:
table_name: table, columns: ['Year', 'Network', 'Play-by-play', 'Color commentator(s)', 'Sideline reporter(s)']

### Response:
SELECT COUNT Year FROM table WHERE Color commentator(s) = frank gifford and dan dierdorf