It is the intent and purpose of the legislature that the several groups of public service companies shall each contribute sufficient in fees to the commission to pay the reasonable cost of regulating the several groups respectively. The commission shall keep accurate records of the costs incurred in regulating and supervising the several groups of companies subject to regulation or supervision and such records shall be open to inspection by all interested parties. The records and data upon which the commission's determination is made shall be considered prima facie correct in any proceeding instituted to challenge the reasonableness or correctness of any order of the commission fixing fees and distributing regulatory expenses.