Year	current US$
2000	2.55784166
2001	4.18122017
2002	8.17087047
2003	3.37702626
2004	2.30875076
2005	2.88692114
2006	1.82347304
2007	3.31506207
2008	4.09755735
2009	2.2236528
2010	1.82428995
2011	1.54465868
2012	4.39489575
2013	1.83492433
2014	23.9176917
2015	29.33435869
2016	2.58760339
2017	3.23898827
2018	4.32248342
2019	4.05967216
2020	2.8252727
2021	6.37490155