Year	current US$
2000	7.67286982
2001	6.22397682
2002	6.05049778
2003	4.57345636
2004	4.77999025
2005	5.42517969
2006	5.96745079
2007	7.20776178
2008	8.67430852
2009	7.74168561
2010	7.74877864
2011	7.51000693
2012	7.18541087
2013	6.66223921
2014	6.20944583
2015	6.5310097
2016	6.73698474
2017	6.71788779
2018	6.74896889
2019	7.24041402
2020	7.1584173
2021	7.87775241