Year	constant 2015 US$
1970	2396.76383175172
1971	2696.614495090558
1972	2420.9212625965465
1973	3018.036019662198
1974	3202.2300943681225
1975	4168.6902509922875
1976	6699.3851560329185
1977	5148.515204656709
1978	3354.318030222648
1979	1581.5366529468722
1980	4812.887175019955
1981	6781.779102705825
1982	6877.66690875226
1983	6304.155253981818
1984	5973.157910583512
1985	4870.0926633969075
1986	3867.299855454286
1987	2769.9132563497747
1988	3694.2216686503725
1989	3140.954063375761
1990	2654.0361644979002
1991	3282.5986370509763
1992	2627.0280478754617
1993	2135.4871990757974
1994	2612.187759900146
1995	2417.9806716476824
1996	2676.602995586256
1997	2805.796059821702
1998	3010.3104060701585
1999	2866.8343126402797
2000	2291.367064911004
2001	2839.8883846345097
2002	3075.40605271535
2003	3042.7626843892617
2004	2926.3121273392267
2005	3191.626957729079
2006	3022.414412054131
2007	2942.790822092636
2008	3049.9767151232154
2009	3067.6350410690957
2010	3080.4727058841104
2011	3432.4297201752215
2012	3707.8047632624457
2013	4035.777290068369
2014	4520.930624099791
2015	4605.245500523417
2016	4532.271906945433
2017	4468.549824746893
2018	5584.5270931635605
2019	5820.083463296014
2020	5258.468437769311
2021	5319.75793496031