Year	current US$
1996	453.31524198888604
1997	513.4895414835174
1998	432.87825288654
1999	286.386820555119
2000	339.60403048250504
2001	416.09366249616966
2002	499.13547879937556
2003	625.5947414636205
2004	850.4655621213402
2005	998.2562070256301
2006	1133.8779327232176
2007	1435.218383201351
2008	2007.0022503580583
2009	1737.6538585523276
2010	2325.8724408587827
2011	2846.273752501822
2012	3043.2465579592977
2013	3304.059408460297
2014	3280.6210089115602
2015	2491.6751358452148
2016	2721.0293022324563
2017	3335.536837016738
2018	3942.5061353301176
2019	4190.865221088054
2020	4098.907694992239
2021	4753.255243796289