Year	current US$
2000	8.6245829
2001	8.47286045
2002	9.45043182
2003	11.29080568
2004	11.91201491
2005	12.23926764
2006	12.38317602
2007	15.31928559
2008	18.26260346
2009	18.9494365
2010	19.48620069
2011	21.91739561
2012	21.50308571
2013	23.47299516
2014	24.65479607
2015	21.51647728
2016	32.84241301
2017	32.50783357
2018	34.80105051
2019	33.20922436
2020	34.84581254
2021	37.36372541