Year US Dollars adjusted for inflation) 1965 2350.46228 1966 2407.33575 1967 3891.63745 1968 6875.53847 1969 8379.7089 1970 9239.1452 1971 9009.46362 1972 9545.33509 1973 7874.48593 1974 8415.42108 1975 9995.58456 1976 11458.94732 1977 10978.14347 1978 10009.71515 1979 9878.48247 1980 9907.33954 1981 10967.23886 1982 11576.72627 1983 12801.78622 1984 14210.54211 1985 15472.95366 1986 15148.19594 1987 14097.12207 1988 14419.34368 1989 15531.12761 1990 14903.15877 1991 15127.1347 1992 15659.78021 1993 15894.17039 1994 15923.71335 1995 16295.7348 1996 16548.97305 1997 17445.22727 1998 17889.47471 1999 17843.03579 2000 18698.39975 2001 19308.42061 2002 18772.80037 2003 17881.31476 2004 17671.57505 2005 17631.93969 2006 18063.25193 2007 18302.31933 2008 19112.19706 2009 19408.63402 2010 19281.00081 2011 17913.93164 2012 18300.41451 2013 17830.30899 2014 17167.05043 2015 16957.85427 2016 16962.34878 2017 16144.40722