Year	current US$
2000	5.92715199
2001	6.29369478
2002	6.86437851
2003	8.37698009
2004	5.39656343
2005	6.45210045
2006	6.42637494
2007	8.37355694
2008	9.67533816
2009	9.07632658
2010	9.59026586
2011	8.59317486
2012	8.42181321
2013	8.88006495
2014	8.27782986
2015	7.30983292
2016	7.29835594
2017	7.32631149
2018	7.50072786
2019	6.32307757
2020	6.17500415
2021	6.79392691