Year	current US$
2000	5.16436807
2001	4.68827053
2002	3.79789527
2003	2.65258314
2004	5.71746419
2005	8.27972459
2006	9.25141869
2007	9.77052958
2008	11.4063874
2009	18.43319456
2010	23.45382885
2011	27.75695457
2012	25.37293094
2013	19.83923849
2014	18.36159883
2015	17.23711054
2016	16.14683372
2017	13.57956562
2018	14.35555676
2019	14.03667195
2020	14.77276311
2021	18.44632344