The additional expense allowance, at the time of the change to the newly defined benefits or premiums, is the sum of one percent of the excess, if positive, of the average amount of insurance at the beginning of each of the first ten policy years subsequent to the change, over the average amount of insurance prior to the change at the beginning of each of the first ten policy years subsequent to the time of the most recent previous change, or, if there has been no previous change, the date of issue of the policy; and one hundred twenty-five percent of the increase, if positive, in the nonforfeiture net level premium.
SDCL 58-15-43.5