Year	constant 2015 US$
1991	20698.770515472974
1992	21492.275874572097
1993	22398.18468438122
1994	23253.15745941436
1995	23935.573704602135
1996	23477.777491577013
1997	24098.52324218648
1998	23843.11504423808
1999	23187.531998167946
2000	22949.537247074568
2001	22239.120630768906
2002	20421.318531369096
2003	20023.483871145716
2004	20510.796099413652
2005	21750.498896099325
2006	22780.785403249625
2007	24335.1061585311
2008	25302.581590546688
2009	24177.844386462883
2010	25696.05731876839
2011	26670.67037535255
2012	26439.06611509031
2013	26775.94370982911
2014	26297.906791836147
2015	26744.40584140818
2016	26304.440784324783
2017	26449.191235747763
2018	25607.908325014923
2019	24338.27525641929
2020	23619.89282734109
2021	22842.62522988104
2022	23262.63229097837