Year current US$ 2000 64.10726600174087 2001 65.39124438803772 2002 65.57781308079501 2003 64.01661482417423 2004 71.99375414539338 2005 81.13801782973633 2006 86.47592801037983 2007 103.28102245779687 2008 124.68348121269719 2009 134.10804398854074 2010 153.83398225092537 2011 170.35426429671742 2012 182.0254842467246 2013 177.7090971119819 2014 172.61058218489822 2015 173.64652973206876 2016 186.28212770091878 2017 193.9018768024503 2018 207.3557957693426 2019 197.2901154122912 2020 179.55264121817012 2021 192.9438414493355