For all policies providing hospital, surgical, medical, or major medical benefit, an insurance company, a nonprofit health service corporation, a fraternal benefit society, and any other entity providing a plan of health insurance or health benefit subject to state insurance regulation shall return benefits to group policyholders in the aggregate of not less than seventy percent of premium received and to individual policyholders in the aggregate of not less than fifty-five percent of premium received. The commissioner shall adopt rules to establish these minimum standards on the basis of incurred claims experienced and earned premiums for the entire period for which rates are computed to provide coverage in accordance with accepted actuarial principles and practices