Year	current US$
2000	7.14404362
2001	8.29471407
2002	10.14660108
2003	12.44706921
2004	14.317915
2005	16.72846594
2006	18.08100271
2007	20.44540592
2008	23.65299236
2009	22.88410215
2010	24.73598551
2011	27.52826989
2012	28.8879056
2013	28.84710286
2014	28.80267088
2015	26.01045537
2016	28.40260428
2017	28.00037944
2018	27.46225719
2019	28.58916777
2020	29.10501113
2021	31.22423366