Year	gross (GPI)
1970	0.83992999792099
1971	0.83925998210907
1972	0.839630007743835
1973	0.864750027656555
1974	0.886420011520386
1975	0.917320013046265
1976	0.943870007991791
1977	0.970820009708405
1978	0.999109983444214
1979	1.00313997268677
1980	1.01140999794006
1981	1.02182996273041
1982	1.01721000671387
1983	1.02015995979309
1984	1.01771998405457
1985	1.01651000976563
1986	1.02109003067017
1987	1.02178001403809
1988	1.01775002479553
1989	1.01388001441956
1990	1.01189994812012
1991	1.01663994789124
1992	1.0159900188446
1993	1.01271998882294
1994	1.00571000576019
1995	1.01300001144409
1996	1.01112997531891
1997	1.01493000984192
1998	1.01998996734619
1999	1.01898002624512
2000	1.01285994052887
2001	1.00998997688293
2002	1.00571000576019
2003	1.00943005084991
2004	1.01056003570557
2005	1.00583004951477
2006	1.00080001354218
2007	1.00030994415283
2008	0.999119997024536
2009	1.00057005882263
2010	0.998040020465851
2011	0.995819985866547
2012	0.994239985942841
2013	0.999210000038147
2014	1.00200998783112
2015	1.00073003768921
2016	0.995899975299835
2017	0.995400011539459
2018	0.995670020580292
2019	0.993659973144531
2020	0.994509994983673