; by— (II) 1/27 . (ii) Notwithstanding clause (i), beginning with calendar year 2025, if the Secretary determines under paragraph (4) that the average annual price of a zero-emission electricity credit for each of the 3 calendar years prior to a calendar year (in this clause referred to as the applicable calendar year ) is less than one half of the respective alternative compliance payment for each of the 3 such prior calendar years, the annual percentage increase for the 1 calendar year that begins 4 years after the end of the applicable calendar year shall be twice the percentage described in clause (i). (B) Baseline zero-emission electricity percentage (i) In general The term baseline zero-emission electricity percentage means, with respect to a retail electricity supplier, the average percentage of the electric energy consumed by all electric consumers of the retail electricity supplier that is zero-emission electricity during calendar years 2017, 2018, and 2019. (ii) Election For any retail electricity supplier served by an Independent System Operator or a Regional Transmission Organization, or participating in a joint unit commitment and centralized economic dispatch system regulated by the Federal Energy Regulatory Commission, the retail electricity supplier may elect to set its baseline zero-emission electricity percentage under clause (i) on the basis of the zero-emission electricity and electric energy consumed by either— (I) all electric consumers of the retail electricity supplier