Beginning with the next term of office, the county superintendent of education in Lamar County shall receive an annual salary which shall not be more than 25 percent in excess of the highest salary paid to any other employee in the county school system. The salary herein provided for the superintendent shall be fixed by the county board of education and shall be payable in equal monthly installments out of the county funds available for such purpose. In addition to such salary, the superintendent shall furnish his or her own automobile and shall be reimbursed for out-of-county and out-of-state travel on official business at the rate of twenty cents ($.20) per mile and on an actual expense basis for any other expenses incurred in performance of official duties.