Year	current US$
2000	2.66175163
2001	2.22560104
2002	2.71252897
2003	2.43639876
2004	2.30305507
2005	2.38830155
2006	2.42254436
2007	2.53289277
2008	2.87288554
2009	2.64688898
2010	2.22486417
2011	2.52782858
2012	6.15760259
2013	6.85377564
2014	7.98831774
2015	7.29828241
2016	5.34427151
2017	5.69095428
2018	6.25596867
2019	6.2455819
2020	5.61016782
2021	6.27284932