Year current US$ 2000 2.292198343239046 2001 3.4079949508697056 2002 4.390724065260868 2003 5.739405332834104 2004 7.521237020471139 2005 8.394915050061236 2006 12.293185916523017 2007 12.556570592105146 2008 12.902476039453818 2009 13.258766024290185 2010 17.912846701949302 2011 22.349818015803802 2012 19.791972084291046 2013 20.703581116247918 2014 20.710706254260177 2015 18.359105152807135 2016 15.246389318816776 2017 13.513724618732992 2018 14.651273551135391 2019 14.324616106515395 2020 14.602717992134304 2021 27.9488961958766