Year	current US$
2000	2.39640027
2001	3.67987941
2002	4.10411276
2003	3.58213322
2004	4.86341974
2005	6.28917603
2006	7.47532877
2007	9.31924187
2008	13.17978505
2009	8.64100326
2010	13.094809
2011	23.66289044
2012	10.64291806
2013	11.07247551
2014	23.41995087
2015	12.29164072
2016	15.08948809
2017	11.58669739
2018	13.48929355
2019	11.10722425
2020	18.68195236
2021	15.98897415