Year	current US$
2000	15.13236345
2001	14.06773243
2002	15.03811032
2003	16.3183864
2004	18.70366531
2005	14.07683916
2006	11.70062891
2007	16.54661259
2008	16.68672993
2009	17.58966659
2010	16.00857487
2011	14.80858201
2012	15.19552917
2013	16.60040773
2014	25.48921039
2015	30.38479965
2016	23.53387699
2017	24.82073262
2018	25.66494442
2019	28.4605623
2020	28.20464931
2021	26.37608221