Year US Dollars adjusted for inflation) 1950 11090 1951 11850 1952 12190 1953 12490 1954 12080 1955 12760 1956 12790 1957 12770 1958 12440 1959 12930 1960 13030 1961 13110 1962 13720 1963 14140 1964 14770 1965 15550 1966 16320 1967 16500 1968 17190 1969 17590 1970 17430 1971 17870 1972 18700 1973 19580 1974 19260 1975 19050 1976 19940 1977 20700 1978 21630 1979 22050 1980 21680 1981 21990 1982 21430 1983 22260 1984 23680 1985 24420 1986 25010 1987 25580 1988 26340 1989 26980 1990 27170 1991 26790 1992 27430 1993 27940 1994 28850 1995 29290 1996 30120 1997 31250 1998 32300 1999 33440 2000 34360 2001 34160 2002 34290 2003 34880 2004 36100