The mayor of the municipality shall establish and maintain a complete system of records for a utility system, park, or swimming pool the revenue of which is encumbered under this chapter that:
(1) shows any free service provided and the value of the free service; and
(2) shows separately the amounts spent and the amounts set aside for operation, salaries, labor, materials, repairs, maintenance, depreciation, replacements, extensions, interest, and the creation of a sinking fund to pay the public securities and debt.