Year US Dollars adjusted for inflation) 1950 6290 1951 6504 1952 6622 1953 6795 1954 7065 1955 7298 1956 7482 1957 7582 1958 7469 1959 7671 1960 8051 1961 8404 1962 8817 1963 9198 1964 9781 1965 10040 1966 10310 1967 10670 1968 11090 1969 11770 1970 12470 1971 12880 1972 13510 1973 14330 1974 14910 1975 14650 1976 15460 1977 15550 1978 16000 1979 16370 1980 17060 1981 16930 1982 17020 1983 17040 1984 17490 1985 17760 1986 18070 1987 18480 1988 19380 1989 20040 1990 20640 1991 20930 1992 21180 1993 20890 1994 21490 1995 21940 1996 22090 1997 22790 1998 23160 1999 23790 2000 24660 2001 24820 2002 25110 2003 25260 2004 25880