Year	current US$
2000	8.79585398
2001	8.80011749
2002	9.66159982
2003	12.02437081
2004	13.19716053
2005	12.98594218
2006	13.50236225
2007	14.44644007
2008	13.98791801
2009	13.938784
2010	13.84208286
2011	15.11019819
2012	16.12028519
2013	16.83440395
2014	18.01644189
2015	16.64524103
2016	16.3534903
2017	16.92735433
2018	17.92371876
2019	17.08781046
2020	18.00657642
2021	19.53630505