Year	current US$
2000	3.87053596
2001	3.75707173
2002	4.22582427
2003	4.52290884
2004	5.63902955
2005	4.16132717
2006	4.63341617
2007	5.53481034
2008	8.77171114
2009	7.5067235
2010	7.60760065
2011	8.83236698
2012	11.65869197
2013	6.22984441
2014	10.68460037
2015	8.17860755
2016	9.91281278
2017	8.94385127
2018	8.71333299
2019	9.57339376
2020	11.5360353
2021	12.64385524