Year	current US$
2000	9.633270554368607
2001	8.73557646782046
2002	8.25232883281556
2003	10.454500945812056
2004	12.248040312674943
2005	13.502461504928155
2006	14.929354932609481
2007	17.07319535425537
2008	17.606626756938685
2009	16.000379357675598
2010	17.793618830057646
2011	18.547243806504458
2012	18.582325187336927
2013	20.479709494726155
2014	18.331428648204987
2015	18.3106711655697
2016	17.05573471752806
2017	15.774921730563237
2018	14.021977290198917
2019	13.900454565883015
2020	12.233113805133462
2021	12.959421580913116