Year current US$ 1991 208.49100496310828 1992 135.1071742711014 1993 141.4963855055576 1994 135.27829837401686 1995 124.94561636857215 1996 177.27457718600823 1997 218.37348691660566 1998 242.1799150639876 1999 283.2721686408181 2000 253.13319623509577 2001 228.63807740185345 2002 214.39004652083136 2003 262.94897333776106 2004 325.7077040947201 2005 358.16318726358134 2006 363.45307360441916 2007 409.0781966512593 2008 478.2292323818178 2009 454.65971963390274 2010 402.07601744900415 2011 503.76064608943585 2012 556.9980359235533 2013 553.9472880432315 2014 553.2255036994392 2015 473.69038972770284 2016 341.67462819671357 2017 356.41218532068933 2018 395.9129653960399 2019 389.8484107090384 2020 340.88112601374314 2021 366.2556650601308