Year US Dollars adjusted for inflation) 1960 8749.05784 1961 9413.23499 1962 9880.86365 1963 10542.29879 1964 10937.69164 1965 11522.66674 1966 11224.44796 1967 11072.08611 1968 12604.09356 1969 13945.75559 1970 14476.72534 1971 14750.56378 1972 16127.11638 1973 16352.9027 1974 16901.49522 1975 17055.63889 1976 16732.8827 1977 16531.77837 1978 17085.99751 1979 17686.52745 1980 17555.37405 1981 18128.19742 1982 18161.40336 1983 18433.07399 1984 18363.52746 1985 18770.86698 1986 19257.14037 1987 20301.47854 1988 20548.91074 1989 20319.36264 1990 21141.29699 1991 21444.75498 1992 22323.83538 1993 22633.17572 1994 23692.85162 1995 24592.24812 1996 25230.31031 1997 25508.75376 1998 25970.83378 1999 26233.30559 2000 27636.34077 2001 26999.36506 2002 26503.84335 2003 26229.39977 2004 26947.4445 2005 27570.94557 2006 28499.32593 2007 29614.07515 2008 29962.00561 2009 29658.52263 2010 30642.94062 2011 31482.99716 2012 31507.47856 2013 32196.35817 2014 32661.29413 2015 32993.31428 2016 33677.46195 2017 34134.80561