Year	current US$
2000	2.4642838605837745
2001	1.7137599312732947
2002	2.042188641577432
2003	2.565286849818739
2004	3.1976693644812166
2005	3.611525781610416
2006	4.131429783982326
2007	4.711167420189132
2008	5.584858388946773
2009	5.4300923425425776
2010	5.867849105378464
2011	7.40856495545835
2012	7.8207948570454064
2013	10.793309793389529
2014	12.180226588623098
2015	10.477651271338113
2016	8.406229815760224
2017	6.712901664225847
2018	6.78220081108584
2019	7.81066464713093
2020	7.6684567028806505
2021	8.70564127285712