Year	current US$
2000	4.465984709700673
2001	4.696510997785133
2002	4.59842004175696
2003	5.400888332511542
2004	5.9293198186170875
2005	7.138682909769356
2006	7.942170162085645
2007	9.453157032955884
2008	10.501423239025167
2009	10.94582445003263
2010	11.134172098671286
2011	11.624528518274449
2012	12.099028744893634
2013	12.758056504643049
2014	13.359058283234488
2015	12.60172971564242
2016	13.268151703004474
2017	13.679928949424898
2018	14.020936295621095
2019	14.642505102626151
2020	16.098449478679605
2021	16.803628135267804