Year current US$ 2000 208.08170779 2001 211.42314479 2002 229.31299497 2003 284.44601237 2004 326.66915123 2005 342.22096924 2006 373.55853277 2007 480.09610187 2008 532.66447151 2009 448.33227254 2010 430.43236807 2011 473.85810285 2012 435.70710781 2013 486.28468724 2014 510.85045062 2015 442.73957589 2016 455.5357205 2017 450.90584204 2018 503.65536854 2019 514.24817279 2020 468.15017528 2021 593.71520822