Year current US$ 2000 2.17241093 2001 2.32513552 2002 2.68899422 2003 2.80840537 2004 3.31123958 2005 6.05636032 2006 6.7959418 2007 5.76138493 2008 7.30302802 2009 7.02997033 2010 6.17177736 2011 6.44541467 2012 5.44821504 2013 7.33420325 2014 7.13802505 2015 5.34786315 2016 5.44770628 2017 9.69988052 2018 10.02233736 2019 11.14250454 2020 13.06805 2021 12.53374796