; and (II) the greenhouse gas emissions of power sources that are not electric energy that were replaced with electric energy provided by the retail electricity supplier which results in such beneficial electrification-related reductions. (C) System support resource For any calendar year in which a generating unit that is owned by a retail electricity supplier has been designated a System Support Resource by the Federal Energy Regulatory Commission and is thereby required, by an Independent System Operator or Regional Transmission Organization, or under a State-regulated resource planning process, to remain in operation because retirement of the generating unit would harm the reliability of the electric energy transmission system, in calculating the total quantity of electric energy consumed by electric consumers of the retail electricity supplier under subparagraph (A)(i), the Secretary shall deduct the quantity of megawatt-hours of electricity generated by such generating unit during such calendar year. (4) Average credit prices For each calendar year, the Secretary shall— (A) analyze the market for zero-emission electricity credits in order to determine the average annual price of zero-emission electricity credits for the calendar year; (B) determine whether the average annual price of a zero-emission electricity credit determined under subparagraph (A) is less than half of the alternative compliance payment under subsection (c) for the calendar year; and (C) publish the determinations made under subparagraphs (A) and (B) by not later than January 31 of the year following the calendar year. (5) Definitions In this subsection: (A) Annual percentage increase (i) Except as provided in clause (ii), the term annual percentage increase means, with respect to a retail electricity supplier, the product obtained by multiplying— (I) the difference between 100 percent and the baseline zero-emission electricity percentage