Year	current US$
2000	3.6821947121512877
2001	4.5238943220663765
2002	4.261612749477428
2003	5.99794840613692
2004	8.85643334576459
2005	9.914794208118343
2006	10.924679003098765
2007	13.448657720695287
2008	17.374122019340557
2009	16.293026673343658
2010	15.328266478331006
2011	17.08233138826553
2012	15.800120508183294
2013	16.85650770086138
2014	16.979390277827996
2015	14.137446716629192
2016	16.63759997690185
2017	15.394594752965686
2018	16.348411463628004
2019	16.85385814229979
2020	17.42758412059599
2021	18.344470223237927