Year	current US$
2000	2.42757424
2001	1.82363706
2002	2.27942359
2003	2.5377712
2004	2.67336969
2005	2.54206863
2006	2.81392511
2007	3.24137164
2008	3.3461322
2009	3.62930659
2010	4.35039989
2011	4.75053385
2012	4.76846127
2013	5.22015237
2014	5.61003404
2015	5.73340587
2016	7.87356598
2017	8.9745517
2018	9.3824752
2019	9.43376367
2020	9.14320207
2021	9.7819054