1. All counties of this state are hereby classified, for the purpose of establishing organization and powers in accordance with the provisions of Section 8, Article VI, Constitution of Missouri, into four classifications determined as follows:
2. The required assessed valuation for each classification under subsection 1 of this section shall be increased annually by an amount equal to the percentage change in the annual average of the Consumer Price Index for All Urban Consumers (CPI-U) or zero, whichever is greater. The state tax commission shall calculate and publish this amount so that it is available to all counties.