Year	current US$
2008	26312544891.9378
2009	31079566081.1961
2010	33342305790.569
2011	37808013807.7185
2012	37976874036.1989
2013	39957123457.443
2014	44121066447.329
2015	40724589475.7649
2016	44266310864.8314
2017	47542305070.9181