Year US Dollars adjusted for inflation) 1970 5241 1971 5034 1972 4911 1973 4783 1974 4837 1975 5034 1976 4939 1977 5310 1978 5269 1979 5207 1980 4973 1981 5366 1982 5452 1983 5236 1984 5122 1985 4862 1986 5034 1987 5565 1988 5222 1989 4959 1990 4467 1991 4931 1992 4982 1993 4876 1994 4894 1995 4899 1996 4869 1997 4843 1998 4805 1999 4917 2000 5269 2001 5108 2002 5298 2003 5557