For purposes of clause (i), the term “years of coverage” with respect to any individual means the number (not exceeding 30) equal to the sum of (I) the number (not exceeding 14 and disregarding any fraction) determined by dividing (a) the total of the wages credited to such individual (including wages deemed to be paid prior to 1951 to such individual under
section 417 of this title, compensation under the Railroad Retirement Act of 1937 [
45 U.S.C. 228a et seq.] prior to 1951 which is creditable to such individual pursuant to this subchapter, and wages deemed to be paid prior to 1951 to such individual under
section 431 of this title) for years after 1936 and before 1951 by (b) $900, plus (II) the number equal to the number of years after 1950 each of which is a computation base year (within the meaning of subsection (b)(2)(B)(ii)) and in each of which he is credited with wages (including wages deemed to be paid to such individual under
section 417 of this title, compensation under the Railroad Retirement Act of 1937 or 1974 [
45 U.S.C. 228a et seq., 231 et seq.] which is creditable to such individual pursuant to this subchapter, and wages deemed to be paid to such individual under
section 429 of this title) and self-employment income of not less than 25 percent (in the case of a year after 1950 and before 1978) of the maximum amount which (pursuant to subsection (e)) may be counted for such year, or 25 percent (in the case of a year after 1977 and before 1991) or 15 percent (in the case of a year after 1990) of the maximum amount which (pursuant to subsection (e)) could be counted for such year if
section 430 of this title as in effect immediately prior to
December 20, 1977, had remained in effect without change (except that, for purposes of subsection (b) of such
section 430 of this title as so in effect, the reference to the contribution and benefit base in paragraph (1) of such subsection (b) shall be deemed a reference to an amount equal to $45,000, each reference in paragraph (2) of such subsection (b) to the average of the wages of all employees as reported to the Secretary of the Treasury shall be deemed a reference to the national average wage index (as defined in
section 409(k)(1) of this title), the reference to a preceding calendar year in paragraph (2)(A) of such subsection (b) shall be deemed a reference to the calendar year before the calendar year in which the determination under subsection (a) of such
section 430 of this title is made, and the reference to a calendar year in paragraph (2)(B) of such subsection (b) shall be deemed a reference to 1992).