Year	current US$
2000	4.94342797
2001	5.28643192
2002	5.97563882
2003	7.66833829
2004	11.59513908
2005	15.12771592
2006	20.97108517
2007	30.75548197
2008	27.46145751
2009	34.17012917
2010	24.89647745
2011	19.08543919
2012	20.79007786
2013	16.92908361
2014	23.54216081
2015	13.94542126
2016	21.25398254
2017	12.82324319
2018	8.27207038
2019	8.06215922
2020	7.97824481
2021	5.83712958