Year	current US$
2000	8.65021672
2001	7.01747469
2002	7.33710977
2003	10.85723737
2004	8.98221665
2005	9.14389458
2006	9.68808611
2007	14.4827114
2008	15.94299296
2009	16.92379002
2010	21.63259834
2011	14.53870698
2012	16.89004215
2013	22.35341705
2014	24.38655316
2015	24.94371471
2016	26.97321411
2017	29.65492171
2018	28.02030864
2019	28.38710435
2020	22.88666557
2021	24.63983862