The annual retirement benefit payable to a judge retiring pursuant to subdivisions (2) through (5) of subsection (a) of Section 12-18-55 shall be 75 percent of the salary payable by the state to district judges on the date such judge retires. Retired district judges shall also be entitled to receive cost-of-living increases in their retirement pay equal to any cost-of-living increment received by retired state employees from the State Employees' Retirement System, as provided by the Legislature from time to time. District judges retirement benefits shall be payable monthly for the life of the beneficiary and shall not be subject to writs of attachment or garnishment.