Year current US$ 1970 2267.450039832439 1971 2534.270486506253 1972 2881.7077382367975 1973 3246.470747077042 1974 3456.50728022862 1975 4064.554993062331 1976 3891.152906131022 1977 4308.658951144235 1978 5473.196929265813 1979 6967.861661784334 1980 8807.363458651009 1981 8319.677751848078 1982 7969.242662703838 1983 7601.090534277744 1984 7145.860908446201 1985 7476.58920370747 1986 9409.889738615224 1987 11526.690504635906 1988 14080.336635694493 1989 14122.779272029935 1990 16398.08194420495 1991 17154.96194289921 1992 17960.75283789092 1993 16162.179534613237 1994 17726.879047972856 1995 19281.295869874077 1996 20267.47456519192 1997 22819.647257644665 1998 24813.523591514415 1999 24834.767237856533 2000 24401.02043315726 2001 24062.701850480804 2002 26117.410793851603 2003 29959.883518764895 2004 35034.76125356103 2005 36605.041787584996 2006 37973.61519314781 2007 42710.9708799221 2008 39510.51714662766 2009 32299.43394017127 2010 33571.199311961114 2011 35752.95819658131 2012 35519.33019401599 2013 36085.94595411855 2014 39539.11649638563 2015 37441.0284183644 2016 34104.35681424501 2017 34065.891026246005 2018 36072.66320837174