Year US Dollars adjusted for inflation) 1970 626.6 1971 671 1972 720.7 1973 782.9 1974 852.1 1975 917.4 1976 987.9 1977 1067 1978 1188 1979 1276 1980 1468 1981 1589 1982 1491 1983 1677 1984 2056 1985 2247 1986 2375 1987 2497 1988 2621 1989 2765 1990 3103 1991 3226 1992 3311 1993 3396 1994 3500 1995 3617 1996 3867 1997 3970 1998 4202 1999 4085 2000 4530 2001 4464 2002 4653 2003 5154 2004 5086