Year current US$ 2008 5461768 2009 3637332 2010 6763433 2011 153379168 2012 177393165 2013 9211171 2014 11574770 2015 9670946 2016 8440321 2017 8123721 2018 19615088 2019 15781389 2020 11771659 2021 17816472