S.C. Code Ann. § 41-35-340: "Rate of insured unemployment" defined.

For purposes of Section 41-35-330 "rate of insured unemployment" means the percentage derived by dividing the:

(1) average weekly number of individuals filing claims for regular state compensation in this State for weeks of unemployment with respect to the most recent thirteen consecutive week period, as determined by the department on the basis of its reports to the United States Secretary of Labor, by

(2) average monthly employment covered under Chapters 27 through 41 of this title for the first four of the most recent six completed calendar quarters ending before the end of this thirteen-week period.