Year US Dollars adjusted for inflation) 1960 1429.99798 1961 1510.25819 1962 1547.83496 1963 1446.47787 1964 1461.71235 1965 1474.62735 1966 1454.05902 1967 1444.12831 1968 1511.09974 1969 1579.01468 1970 1630.60765 1971 1704.77839 1972 1795.67901 1973 1884.33893 1974 1971.46356 1975 2060.64291 1976 2018.7081 1977 1785.01904 1978 1844.32811 1979 1967.48494 1980 2248.05702 1981 2567.76337 1982 3081.76606 1983 3168.04877 1984 3292.42655 1985 3162.20222 1986 2864.09216 1987 2791.56319 1988 2764.4173 1989 2760.26451 1990 2713.10129 1991 2703.519 1992 2699.5731 1993 2600.98948 1994 2391.31033 1995 2418.42675 1996 2452.13807 1997 2368.34013 1998 2387.5613 1999 2260.72982 2000 2364.61292 2001 2387.84864 2002 2430.28515 2003 2383.35912 2004 2395.81962 2005 2503.31205 2006 2573.50988 2007 2447.51163 2008 2496.50231 2009 2595.7485 2010 2737.34233 2011 2751.91068 2012 2782.11188 2013 2806.34743 2014 2922.97318 2015 2925.52775 2016 2771.39734 2017 2576.39612