Any tax imposed on property subject to the taxing power of the community college district under Article X, § 11(a) of the Missouri Constitution without voter approval shall not exceed the annual rate of ten cents on the hundred dollars assessed valuation in districts having one billion five hundred million dollars or more assessed valuation; twenty cents on the hundred dollars assessed valuation in districts having seven hundred fifty million dollars but less than one billion five hundred million dollars assessed valuation; thirty cents on the hundred dollars assessed valuation in districts having five hundred million dollars but less than seven hundred fifty million dollars assessed valuation; forty cents on the hundred dollars assessed valuation in districts having less than five hundred million dollars assessed valuation; except that, no public community college district having an assessed valuation in excess of one hundred million and less than two hundred fifty million which is levying an operating levy of thirty cents per one hundred dollars assessed valuation on September 28, 1975, shall increase such levy above thirty cents per one hundred dollars assessed valuation without voter approval. Tax rates specified in this section that were in effect in 1984 shall not be lowered due to an increase in assessed valuation created by general reassessment; however, the provisions of section 137.073 or § 22(a) of Article X of the Missouri Constitution are applicable. Districts which operate institutions awarding degrees above the associate degree shall not be affected by the changes provided in this section. Increases of the rate with voter approval shall be made in the manner provided in chapter 164 for school districts.