Where the rate of duty in effect at any time is an intermediate stage under
section 2119 of this title, the proclamation made pursuant to subsection (a) may provide for the reduction of each rate of duty at each such stage proclaimed under
section 2111 of this title by not more than 20 percent of such rate of duty, and, subject to the limitation in paragraph (2), may provide for a final rate of duty which is not less than 80 percent of the rate of duty proclaimed as the final stage under
section 2111 of this title.