7-4-2510. Sheriff's office -- longevity payments. Beginning on the date of the deputy sheriff's or undersheriff's first anniversary of employment with the office and adjusted annually, a deputy sheriff or undersheriff is entitled to receive a longevity payment amounting to 1% of the minimum base annual salary for each year of service with the office, but years of service during any year in which the salary was set at the same level as the salary of the prior fiscal year may not be included in any calculation of longevity increases. This payment must be made in equal monthly installments.