If you have served at least three years in the position from which you are retiring, your FAS generally would be the actual gross salary earnable during the 12 months prior to your retirement. If you have served less than three years in the position from which you are retiring, your FAS generally would be your annual earnable salary during the last year of the most recent position you held for at least three years. You may instead elect to have your FAS be your average annual salary earnable during any five consecutive years.