Year	current US$
2000	14.61625494
2001	14.51760593
2002	15.73935166
2003	16.59813112
2004	16.24146518
2005	17.73950599
2006	19.2528734
2007	22.30093912
2008	25.80051397
2009	24.84268468
2010	20.56530244
2011	28.87532986
2012	33.96132311
2013	51.40293989
2014	48.44970204
2015	40.63983275
2016	35.39315135
2017	24.81578935
2018	26.27299942
2019	24.46305283
2020	24.08546536
2021	22.18950801