Every rating organization and every insurer which makes its own rates shall make rates that are not unreasonably high or inadequate for the safety and soundness of the insurer and which do not unfairly discriminate between risks in this state and shall, in rate-making and in making rating plans:
(1) Adopt basis classifications, which shall be used as the basis of all manual, minimum, class, schedule, or experience rates;
(2) Give consideration to past experience within the state and without the state, when necessary, and due consideration may be given to prospective loss experience within the state and without the state, when necessary, over such period of years as appears to be fairly representative of the frequency of the occurrence of the particular risk; and
(3) Give consideration to all factors reasonably related to the kind of insurance involved, including a reasonable profit for the insurer and, in the case of participating insurers, to policyholders' dividends.
The systems of expense provisions included in the rates for use by insurers or groups of insurers may differ from those of other insurers or groups of insurers to reflect the requirements of the operating methods of any such insurer or group with respect to any kind of insurance, or any subdivision or combination thereof, for which the commissioner approves the application of separate expense provisions.