The legislative body which stipulates by law the amount and type of retirement benefits to be paid by a retirement plan covering elected or appointed public officials or both, shall, before taking final action of any substantial proposed change in future benefits, cause to be prepared a statement regarding the cost of such change. Such statement of cost shall be prepared by a qualified actuary with experience in retirement plan financing and such statement shall be available for public inspection. The general assembly shall provide by law applicable standards and requirements governing the preparation, content, and disposition of such statements of cost.