Year current US$ 2000 42.70728091 2001 41.32051305 2002 51.49590822 2003 77.98264561 2004 109.04250498 2005 126.90751273 2006 148.46669266 2007 199.47759128 2008 231.8841404 2009 214.10419858 2010 221.06424754 2011 239.64152765 2012 239.30639918 2013 282.50331459 2014 303.27644026 2015 274.77634395 2016 291.67984722 2017 336.089663 2018 383.15058757 2019 384.82567174 2020 385.96673559 2021 466.09377431