(1) There shall be paid into the retirement fund by contributions of the city, the amounts necessary to pay all pensions and all other benefits allowable under this chapter to members on account of prior service, and minimum allowances provided for in RCW 41.28.130. Until the amount accumulated in the retirement fund becomes at least as large as the present value of all amounts thereinafter payable from said fund the amount annually due to the said fund under this section shall be the amount payable from said fund in the ensuing fiscal year on account of prior service and minimum allowances.