Each circuit clerk in the Fifteenth Judicial Circuit, in addition to the salary paid by the state, shall receive a supplemental salary from the general fund of the county composing the judicial circuit. The supplemental salary shall at all times equal 29 percent of the salary paid each circuit clerk by the State of Alabama and shall be paid in equal installments at the same times and in the same manner that the salaries of the county employees are paid. In no event shall any circuit clerk's total salary, including the supplement, be greater than the combined salary and supplement for the Montgomery County Tax Assessor. The governing body of the county is hereby authorized, empowered, and directed to pay the supplemental salary provided herein to each circuit clerk out of the funds of the county or any other funds as may be available for such purpose. The salary provided herein is in lieu of any other supplemental salary paid by the county and represents the total supplemental salary to be provided by the county for such clerks.