Year	current US$
2000	4.96826778
2001	6.44105276
2002	7.47837919
2003	9.12462624
2004	9.01258879
2005	9.60339546
2006	9.42421623
2007	10.58059834
2008	12.09905808
2009	11.91466392
2010	12.11117745
2011	11.09383742
2012	11.75606972
2013	11.2069935
2014	10.48362376
2015	9.11876534
2016	8.32645615
2017	8.55850931
2018	8.82244083
2019	8.99062086
2020	9.49710255
2021	9.8514489