Year	current US$
2000	8.40154972
2001	7.82960489
2002	6.81995146
2003	7.25081179
2004	7.65156392
2005	7.26139273
2006	7.68945359
2007	8.11294548
2008	6.58189234
2009	10.44891509
2010	11.83937332
2011	12.12187794
2012	13.63477478
2013	14.39276119
2014	16.48761128
2015	11.29375622
2016	13.74954297
2017	10.01900078
2018	11.7433516
2019	11.63539486
2020	11.57365071
2021	12.55499128