The General Assembly shall from time to time make appropriations to the Department of Public Health for distribution to multiple-county and consolidated health departments. Such appropriations shall be distributed to health departments for municipality contributions to the Illinois Municipal Retirement Fund. Distribution shall be made to those health departments, which have no other funds available for payment of municipality contributions, and have certified the amount needed to each county in the health department and one or more of the counties is at a county tax rate of 75? per $100 of equalized valuation for the year for which the contributions are required. The amount distributed shall be equal to the amount which the county or counties would have been required to contribute to the health department for municipality contributions of the health department if their county tax rate was less than 75? per $100 equalized valuation.