An agency is required to prepare a fiscal note on a proposed administrative rule that affects the expenditures or revenues of a unit of local government as provided in N.C. Gen. Stat. § 150B-21.4 (1979, 2nd Sess., c. 1262, s. 8; 1987, c. 827, ss. 1, 55; 1991, c. 418, s. 13.)