(i) the rate of employer contributions under the plan for the first plan year beginning on or after the date on which an amendment increasing benefits is adopted, multiplied by the valuation contribution base for that plan year, equals or exceeds the sum of
(I) the amount that would be necessary to amortize fully, in equal annual installments, by July 1, 1986, the unfunded vested benefits attributable to plan provisions in effect on July 1, 1977 (determined as of the last day of the base plan year); and
(II) the amount that would be necessary to amortize fully, in equal annual installments, over the period described in subparagraph (C), beginning with the first day of the first plan year beginning on or after the date on which the amendment is adopted, the unfunded vested benefits (determined as of the last day of the base plan year) attributable to each plan amendment after July 1, 1977; and
(ii) the rate of employer contributions for each subsequent plan year is not less than the lesser of
(I) the rate which when multiplied by the valuation contribution base for that subsequent plan year produces the annual amount that would be necessary to complete the amortization schedule described in clause (i), or
(II) the rate for the plan year immediately preceding such subsequent plan year, plus 5 percent of such rate.