Year US Dollars adjusted for inflation) 1960 10867.70366 1961 11681.30547 1962 12322.31451 1963 12918.96745 1964 13171.60209 1965 13487.99005 1966 14184.53188 1967 15093.14726 1968 15979.65754 1969 16858.40759 1970 17653.01526 1971 17890.32129 1972 18445.54557 1973 19626.3936 1974 20570.81838 1975 20020.92257 1976 21340.7658 1977 21794.43366 1978 22420.57388 1979 23688.05915 1980 24450.14431 1981 24626.97568 1982 24710.51652 1983 24990.36094 1984 25790.74798 1985 26504.73426 1986 27261.27663 1987 28128.57514 1988 29294.23513 1989 30264.12683 1990 30839.27833 1991 31292.05309 1992 31531.69002 1993 31243.67902 1994 31909.23671 1995 32829.88275 1996 33242.8523 1997 33835.07313 1998 34371.98202 1999 34902.26213 2000 36180.77833 2001 36801.29381 2002 36837.86399 2003 36729.97554 2004 37070.33052 2005 37238.93653 2006 37872.16836 2007 38236.79561 2008 37585.33735 2009 35363.40046 2010 35849.3732 2011 35994.13358 2012 34885.2969 2013 33887.29817 2014 33615.97178 2015 33968.70396 2016 34318.49682 2017 34877.82914