Year	constant 2015 US$
1991	25856.864066801536
1992	25276.813199827677
1993	24407.33963774407
1994	23620.38378705582
1995	22537.090589968077
1996	21666.141103783284
1997	20741.743818682477
1998	19820.63206652687
1999	19518.81918661956
2000	19008.60351653698
2001	18182.48446994772
2002	17601.804992909925
2003	17094.643111832887
2004	16609.392389017863
2005	16053.99519668944
2006	17356.233993040747
2007	17650.1766079734
2008	18305.862880314304
2009	17496.87721277138
2010	17995.61821134181
2011	18280.40533541099
2012	19166.611466569957
2013	19937.219238061316
2014	20398.643323737815
2015	20749.213648081968
2016	20753.468678266974
2017	21363.09494442997
2018	21022.468029939362
2019	20929.962278956427
2020	21632.232765156627
2021	21188.1420455453
2022	19803.003462550507