Year	current US$
2000	4.679138952090356
2001	4.819098580310796
2002	4.9680644066558175
2003	5.581523378508101
2004	6.084238731725918
2005	7.059307672917508
2006	7.725220162369523
2007	9.043252641643516
2008	10.107769921934613
2009	10.489366218874249
2010	10.801865956227472
2011	11.224265023695828
2012	11.639342148878637
2013	12.0460706187429
2014	12.486280556718073
2015	12.033105720809726
2016	12.687022418069853
2017	13.152490937198323
2018	13.55229003694169
2019	14.115576096625562
2020	15.165233732446787
2021	15.861842725337779