Year US Dollars adjusted for inflation) 1960 3264 1961 3356 1962 3664 1963 4360 1964 4799 1965 5459 1966 5875 1967 5821 1968 5956 1969 6528 1970 6988 1971 7475 1972 8043 1973 8798 1974 8639 1975 8656 1976 9556 1977 10720 1978 11740 1979 12340 1980 13330 1981 14200 1982 14460 1983 14970 1984 15970 1985 16080 1986 17410 1987 19350 1988 20760 1989 21180 1990 22000 1991 23190 1992 24500 1993 25620 1994 26620 1995 26890 1996 27160 1997 27920 1998 25490 1999 25360 2000 27240 2001 27020 2002 27160 2003 27660 2004 29640