Year US Dollars adjusted for inflation) 1950 9261 1951 9215 1952 8613 1953 9390 1954 9924 1955 10130 1956 9936 1957 9932 1958 10390 1959 10780 1960 10780 1961 10690 1962 11130 1963 11650 1964 12210 1965 12290 1966 12730 1967 12980 1968 13810 1969 14310 1970 14670 1971 15080 1972 15360 1973 15900 1974 15620 1975 15830 1976 16250 1977 16370 1978 16880 1979 17090 1980 17460 1981 17940 1982 17500 1983 17980 1984 18480 1985 19140 1986 19290 1987 19920 1988 20270 1989 20770 1990 20420 1991 20380 1992 20800 1993 21300 1994 22010 1995 22650 1996 23270 1997 24010 1998 24950 1999 25660 2000 25830 2001 26530 2002 27120 2003 27870 2004 27990