Year current US$ 2007 30000000 2008 46000000 2009 47000000 2010 52000000 2011 51000000 2012 51000000 2013 49000000 2014 51000000 2015 44000000 2016 45000000 2017 43000000 2018 53000000 2019 52000000 2020 14000000