Year	current US$
2000	257.41515116
2001	279.58161431
2002	292.02550928
2003	301.71550336
2004	316.10816026
2005	346.23593757
2006	364.75821397
2007	383.47661553
2008	392.31413586
2009	377.31421271
2010	392.34400341
2011	396.67684403
2012	429.02287703
2013	427.98107087
2014	450.611417
2015	473.74134315
2016	474.75238374
2017	504.48577307
2018	525.21143654
2019	506.29479621
2020	397.18336648
2021	479.80043079