Year	current US$
2000	3.56170869
2001	3.50019243
2002	3.30982863
2003	3.02969295
2004	3.51961606
2005	4.47913787
2006	5.75540454
2007	6.44946666
2008	6.4660912
2009	6.67342266
2010	7.08055346
2011	6.065799
2012	4.60926014
2013	4.34797514
2014	5.76335268
2015	5.68129799
2016	5.43747383
2017	5.73303569
2018	5.22598556
2019	5.10034274
2020	5.53794945
2021	6.15508185