At the end of each fiscal year, the Office shall notify the Secretary of the Treasury of the amount equivalent to (1) interest on the unfunded liability computed for that year at the interest rate used in the then most recent valuation of the System, and (2) that portion of disbursement for annuities for that year which the Office estimates is attributable to credit allowed for military service, less an amount determined by the Office to be appropriate to reflect the value of the deposits made to the credit of the Fund under
section 8334(j) of this title. Before closing the accounts for each fiscal year, the Secretary shall credit to the Fund, as a Government contribution, out of any money in the Treasury of the United States not otherwise appropriated, the following percentages of such amounts: 10 percent for 1971; 20 percent for 1972; 30 percent for 1973; 40 percent for 1974; 50 percent for 1975; 60 percent for 1976; 70 percent for 1977; 80 percent for 1978; 90 percent for 1979; and 100 percent for 1980 and for each fiscal year thereafter.