Year current US$ 2000 10.70797699 2001 10.67344931 2002 10.16337202 2003 15.69318774 2004 48.48688743 2005 77.78336037 2006 98.39365967 2007 91.53160842 2008 89.48839683 2009 75.20236014 2010 74.43836168 2011 62.02803708 2012 44.23504397 2013 31.88826041 2014 28.08649957 2015 28.30636287 2016 29.98961469 2017 32.21965143 2018 22.08553543 2019 20.26714706 2020 19.35755992 2021 37.13268387