Year	current US$
2000	4.22481151
2001	4.1374146
2002	3.15871563
2003	3.15829197
2004	4.65857068
2005	5.05561216
2006	5.44874737
2007	5.1206236
2008	6.25243244
2009	6.9921424
2010	7.31497537
2011	7.36346234
2012	8.28136601
2013	7.01619456
2014	6.13481679
2015	6.10625739
2016	8.26324746
2017	6.70538057
2018	7.30747043
2019	9.40261929
2020	17.0744738
2021	12.47717005