Year	current US$
2000	21.44926189
2001	18.65496249
2002	17.51882106
2003	22.9707858
2004	24.80112647
2005	23.24524871
2006	20.79525065
2007	20.08526482
2008	18.33530916
2009	17.73235294
2010	18.90796279
2011	19.00851487
2012	17.21289649
2013	15.83080323
2014	14.95973248
2015	12.81657269
2016	12.23250353
2017	13.30663887
2018	21.42668595
2019	18.38359745
2020	17.77137974
2021	19.68250785