The actuary shall recommend, and the Division of Pensions shall keep in convenient form, such data as shall be necessary for actuarial valuation of the various funds created by this article. At least once in every 3-year period the actuary shall make an actuarial investigation into the mortality, service and compensation or salary experience of the members and beneficiaries as defined in this article and shall make a valuation of the assets and liabilities of the various funds created by this article. Upon the basis of such investigation and valuation, with the advice of the actuary, the board shall:
(a) Adopt for the retirement system such mortality, service and other tables as shall be deemed necessary; and
(b) Certify the rates of contribution, expressed as a proportion of the compensation of members, which shall be made by the State to the contingent reserve fund.