Year	current US$
2000	2.97097095
2001	3.14309324
2002	3.49908229
2003	4.28805357
2004	5.64305482
2005	5.85733865
2006	12.40686296
2007	15.19613779
2008	16.72370193
2009	16.21465717
2010	16.97496535
2011	15.05325635
2012	15.73441408
2013	15.37573583
2014	14.6530777
2015	12.77857778
2016	12.03562117
2017	14.08688087
2018	16.7622408
2019	15.93111397
2020	14.92695698
2021	17.44608041