Year US Dollars adjusted for inflation) 1970 1768 1971 1818 1972 1769 1973 1794 1974 1845 1975 1871 1976 2107 1977 2141 1978 2272 1979 2339 1980 2612 1981 2557 1982 2329 1983 2278 1984 2283 1985 2265 1986 2199 1987 2120 1988 2160 1989 1945 1990 1950 1991 1905 1992 1781 1993 1898 1994 1712 1995 1912 1996 1873 1997 1882 1998 1931 1999 1934 2000 2069