The municipal income tax rate, or the municipal income tax credit for municipal income taxes paid to another municipality, as set forth in any applicable chapter of the Codified Ordinances of the City, shall be increased, decreased or otherwise changed only by ordinance prepared by Council and enacted by a two-thirds vote of its elected members, and submitted to a vote of the electors of this Municipality at the next regular municipal election, or by the procedures set forth in Section 7.01 or 7.02 of this Charter, relating to initiative and referendum petitions. (Enacted 11-6-90.)