Council shall not enact any ordinance levying a tax on property which is taxable according to value or an income tax except upon approval by a majority of electors of the City voting thereon at a general or special election held not less than 90 days after the adoption by Council of a resolution calling for such election, which resolution shall set forth the rate of the proposed tax and its purposes. This section shall not restrict Council's authority to enact ordinances providing for the issuance of bonds or notes supported by property taxes.