combined earnings

The lump sum provided under subdivision (1) of this subsection shall be in an amount equal to the sum of (A) 1.5 per centum of so much of such individual’s combined earnings for any calendar year after 1950 and before 1954 as is in excess of $3,600, plus (B) 2 per centum of so much of such individual’s combined earnings for any calendar year after 1953 and before 1957 as is in excess of $4,200, plus (C) 2.25 per centum of so much of such individual’s combined earnings for any calendar year after 1956 and before 1959 as is in excess of $4,200, plus (D) 2.5 per centum of so much of such individual’s combined earnings for the calendar year 1959 as is in excess of $4,800, plus (E) 3 per centum of so much of such individual’s combined earnings for each of the calendar years 1960 and 1961 as is in excess of $4,800, plus (F) 3.125 per centum of so much of such individual’s combined earnings for the calendar year 1962 as is in excess of $4,800, plus (G) 3.625 per centum of so much of such individual’s combined earnings for any calendar year after 1962 and before 1966 as is in excess of $5,400, plus (H) 4.2 per centum of so much of such individual’s combined earnings for the calendar year 1966 as is in excess of $6,600, plus (I) 4.4 per centum of so much of such individual’s combined earnings for the calendar year 1967 as is in excess of $6,600, plus (J) 3.8 per centum of so much of such individual’s combined earnings for the calendar year 1968 as is in excess of $7,800, plus (K) 4.2 per centum of so much of such individual’s combined earnings for each of the calendar years 1969 and 1970 as is in excess of $7,800, plus (L) 4.6 per centum of so much of such individual’s combined earnings for the calendar year 1971 as is in excess of $7,800, plus (M) 4.6 per centum of so much of such individual’s combined earnings for the calendar year 1972 as is in excess of $9,000, plus (N) 4.85 per centum of so much of such individual’s combined earnings for the calendar year 1973 as is in excess of $10,800, plus (O) 4.95 per centum of so much of such individual’s combined earnings for the calendar year 1974 as is in excess of $13,200. For purposes of this subsection, the term “combined earnings” shall include “compensation” as defined in section 1(h) of the Railroad Retirement Act of 1937 [45 U.S.C. 228a(h)], “wages” as defined in section 209 of the Social Security Act [42 U.S.C. 409], and “self-employment” income as defined in section 211(b) of the Social Security Act [42 U.S.C. 411(b)].