Year	current US$
2000	46.73692703
2001	38.21402359
2002	36.57312012
2003	28.66201591
2004	32.3373642
2005	33.33732224
2006	33.49129486
2007	35.92889786
2008	39.97063065
2009	34.4699173
2010	32.81699753
2011	30.82727623
2012	29.30704689
2013	25.33724403
2014	17.14346313
2015	19.42744446
2016	20.47114944
2017	21.2003746
2018	22.84936142
2019	22.83255005
2020	26.24802017
2021	24.62883568