Year	current US$
2000	3.22441186
2001	3.02171105
2002	2.98067055
2003	4.2055391
2004	5.49460251
2005	7.23591629
2006	6.39293163
2007	7.54333983
2008	9.20887604
2009	10.12627533
2010	10.9716173
2011	11.82057821
2012	12.1910688
2013	11.29494608
2014	10.8904025
2015	12.76873502
2016	12.49828062
2017	12.46399174
2018	13.33781587
2019	13.79789828
2020	13.76928495
2021	14.0466875