Year	current US$
2000	6.1217122886888
2001	6.0881013466673375
2002	6.814155852086889
2003	7.688933992577603
2004	8.902233685390744
2005	9.704346617272929
2006	10.937898912228757
2007	13.233394781370272
2008	15.202609410007451
2009	15.058913290030091
2010	15.970568872914704
2011	17.235757561140794
2012	18.062325705302182
2013	20.554419468603736
2014	21.440994922685455
2015	22.41467380873053
2016	21.59019654610839
2017	21.285492498847844
2018	20.754906924998025
2019	21.597647312614594
2020	22.05675390891343
2021	22.464780255274157