Year current US$ 2000 56.13910675 2001 53.05221176 2002 57.02854919 2003 78.68141174 2004 79.00400543 2005 89.38618469 2006 66.81880188 2007 69.87314606 2008 77.46207428 2009 76.35579681 2010 74.38393402 2011 84.74559784 2012 86.12266541 2013 124.09713745 2014 118.93055725 2015 84.50744629 2016 109.2252121 2017 116.49388123 2018 108.28024292 2019 106.26776123 2020 158.96191406 2021 186.10397339