(a) For purposes of this section only annually, on or before January 1, the Tax Commissioner shall create a single dwelling residential housing index which shall contain the cost of all single dwelling residential housing in the state. The index shall list the average and median cost of single dwelling residential housing by county and by square footage, if available, commencing with the most expensive to the least expensive.
(b) For purposes of this section only, the Tax Commissioner shall also, annually, on or before January 1, establish:
(1) A single dwelling residential housing index multiplier;