For the purpose of maintaining said fund, there shall be levied, from time to time, as other taxes are levied, such sums as may be necessary to meet the financial requirements thereof as herein set forth; provided, that such sums so levied in any year shall not be more than sufficient to pay the outstanding warrants on said fund and to establish therein a balance, which combined levy, in any one year, shall not exceed five per centum (5%) of the outstanding bonds and warrants guaranteed by said fund. (Ord. 72A, § 2, 1934.)