Year	current US$
2000	34.83924796
2001	27.85263451
2002	27.36390562
2003	20.93026789
2004	22.89880355
2005	22.85652994
2006	22.07509877
2007	23.60051031
2008	25.04388993
2009	19.73608918
2010	17.75324442
2011	15.95380652
2012	13.84027034
2013	11.65881009
2014	4.79920015
2015	6.79017714
2016	5.47091667
2017	7.77710665
2018	8.79292274
2019	6.18951557
2020	2.01512863
2021	4.27391215