Sec. 8. EQUALIZATION FUND.  The County Board of Education shall at its August meeting set aside such county available school funds as may have accrued from investments of the permanent school funds and land leases and shall supplement this with an amount not exceeding 5% of the State available school funds apportioned to the county, to be used as an equalization fund to be distributed by the County Board, under such rules and regulations as may be adopted by the County Board, provided that no district shall participate in this distribution that does not levy a local tax for school purposes of at least 75 cents on each one hundred dollars property valuation of such district.