Year	constant 2015 US$
1991	29822.26043724902
1992	30092.745458004116
1993	29926.007339758682
1994	29587.4104893968
1995	29657.29010903033
1996	28434.22137771008
1997	29336.610746870752
1998	27831.799010249684
1999	27076.206182712493
2000	26737.496146673722
2001	27365.85127517276
2002	27210.66480381641
2003	26782.428694079103
2004	26453.601759098852
2005	26716.239177851385
2006	27940.89984511932
2007	29713.391171707124
2008	29747.514568625196
2009	29633.38678401467
2010	30077.221197886476
2011	30999.642320261737
2012	32386.349274859906
2013	33547.438990353214
2014	33382.799423792334
2015	32978.222437188924
2016	32400.41307207632
2017	32819.32006355843
2018	32262.272349028375
2019	33781.56025426704
2020	34288.59651426638
2021	33701.4749775594
2022	34328.296531268636