(1) Upon each person engaging or continuing in the business of operating a railroad, tax is assessed as follows:

For each railroad whose average earnings per mile are greater than Thirty-six Thousand Dollars ($36,000.00), the tax shall be Ninety Dollars ($90.00) per mile.

For each railroad whose average earnings per mile are greater than Thirty-two Thousand Dollars ($32,000.00), but not more than Thirty-six Thousand Dollars ($36,000.00), the tax shall be Eighty Dollars ($80.00) per mile.

For each railroad whose average earnings per mile are greater than Twenty-eight Thousand Dollars ($28,000.00), but not more than Thirty-two Thousand Dollars ($32,000.00), the tax shall be Seventy Dollars ($70.00) per mile.

For each railroad whose average earnings per mile are greater than Twenty-four Thousand Dollars ($24,000.00), but not more than Twenty-eight Thousand Dollars ($28,000.00), the tax shall be Sixty Dollars ($60.00) per mile.

For each railroad whose average earnings per mile are greater than Twenty Thousand Dollars ($20,000.00), but not more than Twenty-four Thousand Dollars ($24,000.00), the tax shall be Fifty Dollars ($50.00) per mile.

For each railroad whose average earnings per mile are greater than Sixteen Thousand Dollars ($16,000.00), but not more than Twenty Thousand Dollars ($20,000.00), the tax shall be Forty Dollars ($40.00) per mile.

For each railroad whose average earnings per mile are greater than Twelve Thousand Dollars ($12,000.00), but not more than Sixteen Thousand Dollars ($16,000.00), the tax shall be Thirty Dollars ($30.00) per mile.

For each railroad whose average earnings per mile are greater than Eight Thousand Dollars ($8,000.00), but not more than Twelve Thousand Dollars ($12,000.00), the tax shall be Twenty Dollars ($20.00) per mile.

For each railroad whose average earnings per mile are greater than Four Thousand Dollars ($4,000.00) per mile, but not more than Eight Thousand Dollars ($8,000.00), the tax shall be Ten Dollars ($10.00) per mile.

For each railroad whose average earnings per mile are less than Four Thousand Dollars ($4,000.00) per mile, the tax shall be Five Dollars ($5.00) per mile.

(2) For the purposes of subsection (1) of this section, the average earnings per mile for a railroad shall be calculated for each line or branch operated in this state based on the proportion that the gross receipts from business for the line or branch bears to the number of miles operated at the close of the preceding business year. If the railroad line or branch is new or had no earnings during the preceding business year, the tax shall be Five Dollars ($5.00) per mile.