Year	current US$
2000	5.51802408
2001	5.765189
2002	6.16118443
2003	6.77713661
2004	7.32355359
2005	7.9789207
2006	8.55761954
2007	10.01204736
2008	11.31457278
2009	12.86678612
2010	14.89984711
2011	16.53207695
2012	16.94821841
2013	19.71822277
2014	22.15753991
2015	25.19310766
2016	29.24768422
2017	30.7448802
2018	32.75333948
2019	35.58224494
2020	38.78175141
2021	43.73179148