Accounts shall be kept for each public utility owned or operated by the city, distinct from other city accounts and in such manner as to show the complete financial results of such city ownership, or ownership and operation, including all assets, liabilities, revenues, and expenses. These accounts shall show the actual costs to the city of each public utility owned; the cost of all extensions, additions and improvements; all expenses of maintenance; the amounts set aside for sinking fund purposes, and, in the case of city operation, all operation expenses of every description. They shall show as nearly as possible the value of any service furnished to or rendered by any such public utility by or to any other city or governmental department or office. They shall also show a proper allowance for depreciation, insurance, interest on the investments, and the estimates of the amount of taxes that would be chargeable against the property if privately owned. The commission shall annually cause to be made and printed for public information a report showing the financial results of such city ownership, or ownership and operation, which report shall give the information specified in this section and such other information as the commission shall deem expedient.