Year current US$ 2000 159.24748813 2001 167.47007762 2002 190.67919057 2003 278.84142383 2004 348.77124581 2005 405.13700618 2006 466.19993419 2007 647.86504283 2008 818.62908105 2009 768.42249577 2010 709.1854657 2011 786.46956597 2012 795.68408718 2013 889.54266561 2014 959.61215815 2015 860.56231806 2016 912.33091325 2017 992.23492391 2018 1143.16683814 2019 1189.42264281 2020 1377.96336326 2021 1595.23214717