Year	constant 2015 US$
1989	20482.97951369759
1990	19680.389946357267
1991	18461.946646093616
1992	17172.18017646088
1993	16751.40575679761
1994	16779.017165932262
1995	17671.514435391055
1996	18477.358763473138
1997	19866.42956440035
1998	21811.05761827021
1999	23223.815037482073
2000	23412.2071632613
2001	23252.81719207832
2002	23782.078102553944
2003	23293.375137723546
2004	22621.780693743858
2005	24124.302565392725
2006	24492.39229344348
2007	24445.110691600024
2008	23236.91227127056
2009	20610.934490673004
2010	20532.479502440918
2011	19835.939521096047
2012	18797.581947522413
2013	18275.838912150633
2014	19079.15729369766
2015	19192.150691245413
2016	19320.53020210413
2017	20402.071988272233
2018	20352.82056785693
2019	18110.721553433654
2020	14748.392077975455
2021	17989.371902131687
2022	18324.954332756042
2023	20655.39987442318