Year	current US$
2000	3.58868511
2001	2.85392033
2002	3.70542499
2003	7.09632247
2004	7.49302092
2005	7.83968478
2006	7.98927012
2007	9.23823523
2008	8.86840598
2009	9.85417675
2010	11.86573781
2011	12.6376769
2012	17.15221023
2013	17.4671096
2014	18.37881665
2015	19.10591636
2016	19.56265854
2017	13.75767604
2018	13.38750223
2019	20.51606702
2020	20.62325263
2021	22.63878906