(b) Commencing in calendar year 1990, the aggregate unused housing tax credit dollar amount of all home rule jurisdictions available pursuant to Section 42 of the Internal Revenue Code of 1986, as amended, shall be as of June 1 of each calendar year reserved to the Authority for allocation by the Authority in the same manner as the Authority allocates low-income housing tax credits allocated to the State; provided that this reservation shall not apply to the housing tax credit amount of a city with over 2,000,000 inhabitants. This amendatory Act of 1989 is intended to alter the allocation of low-income housing tax credits to home rule units, other than a municipality with over 2,000,000 inhabitants otherwise conferred pursuant to Section 42 of the Internal Revenue Code of 1986, as amended.