Year	current US$
2000	3.5496333
2001	13.04270136
2002	14.4292102
2003	16.91552047
2004	23.34065178
2005	22.94952989
2006	21.395223
2007	26.35199595
2008	29.36861738
2009	18.61557314
2010	18.69847857
2011	21.93691855
2012	21.45941085
2013	30.50516413
2014	35.13852749
2015	36.08552844
2016	33.13377014
2017	38.50606914
2018	30.42537181
2019	21.37397486
2020	15.26226816
2021	15.02278037