Year current US$ 2000 0 2001 0 2002 0 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0 2009 1 2010 1 2011 1 2012 1 2013 1 2014 1 2015 1 2016 1 2017 1 2018 1 2019 1 2020 2 2021 2