Year	constant 2015 US$
1988	3931.185662815398
1989	2218.48987658569
1990	2753.854252101885
1991	4033.589231146566
1992	4597.990643661889
1993	4995.118782095643
1994	5303.672410066409
1995	5543.759159287862
1996	6055.336541243226
1997	6010.007833489375
1998	6124.113958663357
1999	5989.817747735198
2000	5970.974546274713
2001	6103.394311255095
2002	6230.746034290117
2003	6348.806484656668
2004	6669.253069043255
2005	6747.711859525934
2006	6740.741877459318
2007	7230.858588892282
2008	7760.765846989421
2009	8445.102470391925
2010	9037.085808791246
2011	9026.471722713597
2012	9019.69822923935
2013	8539.566078289876
2014	7921.080235582198
2015	7802.751367697762
2016	8101.709668356672
2017	8374.740359000309
2018	8435.637354027023
2019	8081.74334362085
2020	6485.726039869148
2021	6107.45470909137
2022	6183.243914542549
2023	6330.5720406589