In any rule adopted by the Land Conservation and Development Commission that establishes a farm income standard to determine whether a dwelling is customarily provided in conjunction with farm use on a tract, the commission shall allow a farm operator to satisfy the income standard by earning the required amount or more of farm income on the tract:
(1) In at least three of the last five years;
(2) In each of the last two years; or
(3) Based on the average farm income earned on the tract in the best three of the last five years.