Year US Dollars 2008-01-01 6330000000000 2009-01-01 8520000000000 2010-01-01 6450000000000 2011-01-01 5640000000000 2012-01-01 7820000000000 2013-01-01 3790000000000 2014-01-01 3790000000000 2015-01-01 4000000000000 2016-01-01 4300000000000 2017-01-01 4610000000000 2018-01-01 4950000000000 2019-01-01 5320000000000 2020-01-01 5710000000000 2021-01-01 6110000000000