SECTION 9-2.   REFERENDUM.
   Council may by an affirmative vote of four members submit any proposed ordinance to a vote of the people. This ordinance shall not be subject to initiative as provided by this Charter.
   The electors shall have the power to approve or reject at the polls any ordinance passed by Council on any matter not pre-empted by this Charter, the Ohio Constitution, or the General Law. Within thirty days after the enactment by Council of any ordinance, a petition signed by qualified electors equal in number to at least fifteen percent of the number voting in the last general election shall cause Council to place the issue upon the ballot.