Year	current US$
2000	9.34243550468803
2001	8.94578747426959
2002	9.424998706389768
2003	12.151418519646807
2004	13.194636278855569
2005	15.181736898866877
2006	18.227331418489648
2007	20.626231980159297
2008	23.446600143467126
2009	22.524073602905993
2010	24.476885180482558
2011	26.24252705548088
2012	27.223621624216094
2013	29.895905169615453
2014	30.79503978847439
2015	30.391561516392372
2016	29.038453337384915
2017	28.06711495485009
2018	27.01666383889801
2019	27.507745400436672
2020	28.244567151564798
2021	31.486123777352553