Year	current US$
2000	9.19439319
2001	9.34881736
2002	10.49735213
2003	13.2989445
2004	15.38992942
2005	16.16598657
2006	17.60787065
2007	20.75534984
2008	24.1446864
2009	24.64554241
2010	23.1269181
2011	24.59096648
2012	21.31853882
2013	22.15886247
2014	22.2909689
2015	18.72250934
2016	24.19690194
2017	24.01712171
2018	23.96071207
2019	24.84047787
2020	20.35581138
2021	19.38410955