Year	current US$
2001	533.50244765
2002	557.95943183
2003	579.86522416
2004	659.02222554
2005	647.05499344
2006	660.79134057
2007	735.41715648
2008	834.42712683
2009	786.9744199
2010	507.4744977
2011	506.56365473
2012	493.50408117
2013	454.60682286
2014	498.41287627
2015	484.89786574
2016	452.1221548
2017	459.15647937
2018	445.90022625
2019	432.46170066
2020	394.09607042
2021	489.87438695