S.C. Code Ann. § 9-1-1060

On the basis of regular interest and of such mortality and other tables as shall be adopted by the Board, the actuary engaged by the Board to make each annual valuation during the period over which the accrued liability contribution is payable, immediately after making such valuation, shall determine the uniform and constant percentage of the earnable compensation of the average new entrant throughout his entire period of active service which would be sufficient to provide for the payment of any employer annuity payable on his account. The rate per cent so determined shall be known as the "normal contribution rate." After the accrued liability contribution has ceased to be payable, the normal contribution rate shall be the rate per cent of the earnable compensation of all members obtained by deducting from the total liabilities of the employer annuity accumulation fund the amount of the funds in hand to the credit of that account and dividing the remainder by one per cent of the present value of the prospective future earnable compensation of all members as computed on the basis of the mortality and service tables adopted by the Board and regular interest. The normal rate of contribution shall be determined by the actuary after each valuation.