Year US Dollars adjusted for inflation) 1959 2689 1960 3067 1961 3218 1962 3094 1963 3142 1964 2807 1965 2865 1966 2851 1967 2749 1968 2728 1969 2637 1970 2319 1971 2374 1972 2335 1973 2310 1974 2380 1975 2398 1976 2560 1977 2434 1978 2516 1979 2463 1980 2546 1981 2464 1982 2474 1983 2297 1984 2163 1985 2107 1986 2146 1987 2146 1988 2253 1989 2233 1990 2196 1991 2158 1992 2188 1993 2207 1994 2130 1995 2261 1996 2323 1997 2392 1998 2543 1999 2553 2000 2546 2001 2721 2002 2853 2003 2888 2004 2934