Mo. Rev. Stat. § 86.163

The total amount payable in each year to the pension accumulation fund shall be not less than the sum of the rates percent known as the normal contribution rate and the accrued liability contribution rate of the total compensation earnable by all members during the year; provided, however, that the aggregate payment by the said cities shall be sufficient when combined with the amount in the fund to provide the pensions and other benefits payable out of the fund during the then current year.