Year current US$ 2007 435610183.15879 2008 501693520.09114 2009 426321526.931219 2010 424064401.57794 2011 471601973.599969 2012 356186698.842048 2013 388740964.524908 2014 345110445.060126 2015 325018604.160601 2016 415137898.615408 2017 398330956.390061 2018 519376330.11062 2019 540356390.303208 2020 429829224.04506 2021 450967278.212846