; by (II) the ratio of the appropriation for the current fiscal year to the appropriation for the prior fiscal year. (ii) Exception for grantees that use less than 80 percent of the amount of a grant Subject to subparagraph (D), if a State, territory, or commonwealth expends less than 80 percent of the amount of a grant under the program for the prior fiscal year before the end of the period of the grant for the prior fiscal year established under paragraph (3)(C)(iii)(I), for purposes of applying subparagraph (B) of this paragraph, if appropriations are not reduced, or applying clause (i) of this subparagraph, if appropriations are reduced, the Administrator shall substitute for the amount received by the State, territory, or commonwealth under a grant under the program for the prior fiscal year the difference obtained by subtracting— (I) the amount equal to 50 percent of the amount remaining available under the grant under the program to the State, territory, or commonwealth for the prior fiscal year, as of the last day of such period