Year	current US$
2000	5.95431006
2001	6.37046768
2002	7.04623699
2003	8.3792806
2004	9.20937821
2005	10.51196139
2006	10.90929962
2007	12.34468818
2008	14.3560348
2009	14.45620949
2010	14.29337131
2011	15.5922795
2012	14.14501025
2013	14.20751425
2014	14.45475322
2015	14.06075811
2016	13.67039025
2017	14.83791044
2018	16.51079931
2019	15.31677802
2020	16.29672107
2021	16.89972122