Year	current US$
2000	2.99511585
2001	1.24154704
2002	1.31952564
2003	2.23338887
2004	2.74732989
2005	2.93709779
2006	3.55503165
2007	4.08010592
2008	4.85788736
2009	4.22700846
2010	4.72992276
2011	6.53005318
2012	7.66630129
2013	12.54460374
2014	13.03114832
2015	9.54720075
2016	8.07170368
2017	5.52714411
2018	4.71035466
2019	8.18515666
2020	6.68554536
2021	6.59327882