Year current US$ 2000 31.09416771 2001 35.96975327 2002 35.96072769 2003 37.33245468 2004 46.10057831 2005 46.69151688 2006 54.01427841 2007 64.43791199 2008 57.31074142 2009 59.43021393 2010 71.98933411 2011 77.32337952 2012 83.64318848 2013 85.9859848 2014 86.81033325 2015 96.52057648 2016 97.18308258 2017 103.39090729 2018 101.69933319 2019 115.32080841 2020 133.70314026 2021 120.43117523