Year	current US$
2000	23.00282097
2001	22.04349136
2002	25.15307426
2003	25.93502045
2004	26.76063919
2005	19.94359016
2006	16.35091019
2007	22.80706406
2008	23.25375366
2009	24.00493431
2010	22.8732872
2011	24.42393684
2012	23.99205208
2013	26.22439003
2014	37.0862999
2015	43.94221497
2016	38.91920853
2017	33.02272034
2018	35.30637741
2019	42.68258667
2020	41.6195488
2021	44.68689728