With respect to loss ratio standards, a Medicare supplement contract shall not be advertised, solicited, or issued for delivery unless the contract can be expected, as estimated for the entire period for which prepaid or periodic charges are computed to provide coverage, to return to subscribers and enrollees in the form of aggregate benefits under the contract, not including anticipated refunds or credits provided under the contract, at least 75 percent of the aggregate amount of charges earned in the case of group contracts, or at least 65 percent of the aggregate amount of charges earned in the case of individual contracts, on the basis of incurred claims or costs of health care services experience and earned prepaid or periodic charges for that period and in accordance with accepted actuarial principles and practices.