Year US Dollars adjusted for inflation) 1960 6961 1961 7328 1962 7778 1963 7467 1964 7624 1965 8093 1966 8287 1967 9163 1968 9377 1969 10600 1970 11620 1971 12030 1972 12280 1973 12120 1974 12400 1975 11530 1976 11300 1977 11770 1978 12410 1979 13400 1980 13480 1981 12890 1982 12660 1983 12860 1984 13580 1985 13450 1986 14360 1987 14820 1988 15030 1989 15170 1990 14580 1991 14330 1992 13740 1993 13270 1994 13590 1995 14020 1996 14240 1997 14540 1998 15050 1999 15540 2000 16090 2001 15500 2002 15450 2003 15710 2004 15940