Year US Dollars adjusted for inflation) 1960 1263 1961 1346 1962 1394 1963 1502 1964 1575 1965 1787 1966 1841 1967 2011 1968 2100 1969 2232 1970 2375 1971 2641 1972 2879 1973 3408 1974 3244 1975 3548 1976 4246 1977 4484 1978 5152 1979 5403 1980 5627 1981 5827 1982 5956 1983 6217 1984 6580 1985 6533 1986 6644 1987 6678 1988 6573 1989 6011 1990 5637 1991 4914 1992 4511 1993 4582 1994 4801 1995 5236 1996 5519 1997 5282 1998 5145 1999 5147 2000 5211 2001 5475 2002 5789 2003 6058 2004 6586