Year	constant 2015 US$
1976	6228.13916015625
1977	7580.255859375
1978	8033.22802734375
1979	9143.43359375
1980	9552.2041015625
1981	9221.7373046875
1982	9803.91015625
1983	10103.8837890625
1984	11279.5888671875
1985	11694.8564453125
1986	11604.7880859375
1987	12560.7099609375
1988	13659.25390625
1989	14944.8388671875
1990	15214.767578125
1991	14380.994140625
1992	15935.39453125
1993	14497.44140625
1994	15148.3212890625
1995	15590.67578125
1996	15487.6318359375
1997	15500.9833984375
1998	18126.759765625
1999	17218.859375
2000	17515.93359375
2001	18683.68359375
2002	19318.740234375
2003	20265.62109375
2004	20759.70703125
2005	21276.798828125
2006	21747.041015625
2007	22310.8203125
2008	23651.31640625
2009	22790.52734375
2010	22375.654296875
2011	22793.35546875
2012	20812.015625
2013	19136.060546875
2014	18629.9140625
2015	20165.8515625
2016	21037.00390625
2017	22382.255859375
2018	23196.30859375
2019	23722.703125
2020	21446.685546875
2021	22323.00390625