Year current US$ 2000 0.98835283 2001 0.76182327 2002 0.77563652 2003 0.49288636 2004 1.56220438 2005 0.258666 2006 0.51356771 2007 0.49076562 2008 0.37752001 2009 1.07255837 2010 2.19816959 2011 3.48605994 2012 1.18803416 2013 0.66435835 2014 1.39876127 2015 0.62700344 2016 0.59143864 2017 0.62085612 2018 0.73755378 2019 1.2406552 2020 1.01906998 2021 0.99353755