Year	current US$
2000	3.94877398
2001	4.18476013
2002	5.35997355
2003	5.86257396
2004	9.98554622
2005	9.53667538
2006	7.15458398
2007	8.28520695
2008	7.47486409
2009	7.51239783
2010	7.65801819
2011	8.16092241
2012	9.20603803
2013	11.2928063
2014	12.46413996
2015	7.44979919
2016	5.75129887
2017	4.6527224
2018	4.59823476
2019	4.76420608
2020	5.98552348
2021	6.16148728