(a) For purposes of determining the amount of annual compensation which a county shall pay to a county commissioner, a judge of probate, a sheriff, a tax assessor, a tax collector, a revenue commissioner, a license commissioner, and an elected assistant tax assessor or collector, the 67 counties of the state shall be placed in categories based on population according to the most recent federal decennial census.
(b) The population categories of counties are as follows:
(1) CATEGORY 1. Population in excess of 450,000.
(2) CATEGORY 2. Population from 350,001 to 449,999.
(3) CATEGORY 3. Population from 200,001 to 350,000.
(4) CATEGORY 4. Population from 50,001 to 200,000.
(5) CATEGORY 5. Population from 19,000 to 50,000.
(6) CATEGORY 6. Population of less than 19,000.