Year US Dollars adjusted for inflation) 1960 390.82973 1961 405.79864 1962 422.17203 1963 435.68989 1964 453.07897 1965 466.26218 1966 481.78585 1967 495.38528 1968 531.21392 1969 592.67139 1970 672.22736 1971 818.68457 1972 1000.80926 1973 1173.45171 1974 1232.45501 1975 1288.41151 1976 1372.39063 1977 1478.52106 1978 1625.44945 1979 1753.75607 1980 1891.40967 1981 1988.88484 1982 2153.10404 1983 2353.79727 1984 2471.15711 1985 2563.03352 1986 2687.31788 1987 2917.43605 1988 3384.48086 1989 3718.48569 1990 3860.0086 1991 4034.26086 1992 4040.42667 1993 4010.78715 1994 4053.43604 1995 4237.5673 1996 4386.85154 1997 4641.80548 1998 4585.73993 1999 4939.59806 2000 4954.77429 2001 4891.91484 2002 5115.89989 2003 5280.21517 2004 5349.00202 2005 5512.81123 2006 5883.89906 2007 6270.47408 2008 6552.77664 2009 5948.85325 2010 6346.1562 2011 6610.33192 2012 6779.3939 2013 7409.42116 2014 7574.2821 2015 7308.76062 2016 7485.04391 2017 7523.21632