Year	current US$
2000	4.51681249
2001	5.51647383
2002	6.95810265
2003	8.37532824
2004	7.90186295
2005	7.36439512
2006	7.63446027
2007	7.4586877
2008	8.12867278
2009	6.47757249
2010	5.62319952
2011	8.58246783
2012	9.17709106
2013	7.4898093
2014	9.62342078
2015	5.09252825
2016	5.21841152
2017	2.0896849
2018	5.60053475
2019	6.260494
2020	9.34589215
2021	8.08293382