Year	current US$
2000	1.16921516
2001	1.26315731
2002	1.4871811
2003	1.98404738
2004	2.43270685
2005	2.71367874
2006	3.04818807
2007	3.69925748
2008	4.4164798
2009	5.03704766
2010	8.11417708
2011	8.29309592
2012	9.11822819
2013	8.14077573
2014	8.75690192
2015	7.11912808
2016	7.72910547
2017	8.53730117
2018	9.01252125
2019	7.5622961
2020	7.98629125
2021	5.37878785