Year	current US$
2000	8.6186285
2001	8.41617775
2002	9.37759209
2003	10.3110857
2004	11.10974789
2005	11.61940002
2006	12.37925339
2007	14.41430759
2008	15.99568462
2009	18.20583725
2010	21.15062714
2011	23.28593445
2012	23.89686203
2013	27.40725899
2014	30.29579544
2015	33.53680038
2016	39.55920792
2017	42.27734375
2018	44.74491119
2019	47.66782379
2020	50.66413116
2021	57.93856812