Year	current US$
2000	2.02162865
2001	2.29478853
2002	1.90593773
2003	1.54958197
2004	3.04369241
2005	3.11823424
2006	3.93079296
2007	4.20593112
2008	3.03580826
2009	4.24191991
2010	4.42046301
2011	8.20740504
2012	6.35879598
2013	3.72196312
2014	7.18488471
2015	7.00206759
2016	6.0691565
2017	5.72610097
2018	5.43661334
2019	5.77146389
2020	5.45310142
2021	5.93988118