Year	constant 2015 US$
1991	10707.90521349841
1992	11190.32842383786
1993	11213.528195917374
1994	10422.2021469756
1995	10496.321290487802
1996	10107.700509729022
1997	10105.496742064384
1998	9910.107625499308
1999	9784.647613772984
2000	10448.918519694913
2001	10365.147786497546
2002	10271.627580066783
2003	10138.802945675152
2004	9873.074912053968
2005	9399.067922324088
2006	8942.3658554685
2007	8326.061118367268
2008	8114.082268263394
2009	7562.13275436522
2010	7096.730550906341
2011	7032.321640317633
2012	6918.259176242396
2013	6725.6999802637865
2014	6597.238840475366
2015	6516.621239904567
2016	6455.770063065561
2017	6408.6299266248225
2018	6239.367755175221
2019	6091.788632991899
2020	5872.232576332422
2021	5665.672611146768
2022	5613.027590958162