122.13  Administration of law; appropriation.--The department shall make such rules as are necessary for the effective administration of this chapter, and the cost is hereby annually appropriated and shall be paid into the State and County Officers and Employees' Retirement Trust Fund out of the Intangible Tax Fund in the State Treasury in the amount necessary to administer efficiently the state and county retirement law. At the end of each fiscal year, beginning with fiscal year 1959-1960, the administrative cost of the state and county retirement system for the fiscal year just ended shall be refunded to the General Revenue Fund from interest earned on investments made subsequent to June 30, 1959.