Year	current US$
2000	3.10712183
2001	3.21432972
2002	3.26103362
2003	3.81782035
2004	5.20465563
2005	5.37500037
2006	6.36999395
2007	7.40865388
2008	8.9478954
2009	9.64807753
2010	9.91536352
2011	11.12203451
2012	10.93993586
2013	14.22297035
2014	13.07613434
2015	11.68816142
2016	12.44182903
2017	13.64406921
2018	13.97500933
2019	14.24889954
2020	18.76734085
2021	19.73198942