Either a specific schedule of premium rates, or a methodology for determining premium rates, must be established in accordance with actuarial principles for various categories of enrollees, provided that the premium applicable to an enrollee may not be individually determined based on the status of the enrollee’s health. However, the premium rates may not be excessive, inadequate, or unfairly discriminatory. A certification by a qualified actuary or other qualified person acceptable to the commissioner as to the appropriateness of the use of the methodology, based on reasonable assumptions, shall accompany the filing along with adequate supporting information.