Year current US$ 2011 50806259446.249 2012 58519330482.8434 2013 61202161210.0914 2014 62715105556.1618 2015 36552670390.6112 2016 31271222010.7257 2017 37249066645.1403 2018 45764938660.2269 2019 36580643424.5758 2020 25344046191.4622 2021 45068213268.7227