Year	current US$
2000	8.446942540527212
2001	8.221760427237458
2002	8.904791075160027
2003	9.70726929314301
2004	10.893456459079502
2005	11.728754960575303
2006	13.183903551295472
2007	15.662381733079089
2008	18.252737069009704
2009	18.35894533831195
2010	19.3445724265049
2011	20.828458856143016
2012	21.40220435368271
2013	23.622353121499835
2014	24.17673627774885
2015	24.530470039533967
2016	23.830779142627623
2017	23.367094279544787
2018	23.205836492065853
2019	24.18216252093933
2020	24.70281706569974
2021	25.545509572469033