Year current US$ 2000 0.67302974 2001 0.8273523 2002 0.93698418 2003 0.99617744 2004 1.11282451 2005 1.09841056 2006 1.00770857 2007 1.16088794 2008 1.33497934 2009 1.70974538 2010 1.90037988 2011 2.00332447 2012 2.18018242 2013 2.46888566 2014 2.52822312 2015 2.61028736 2016 2.4379541 2017 2.55791216 2018 2.60909847 2019 2.65181561 2020 2.7391753 2021 4.42487536