Year	gross (GPI)
1970	0.950039982795715
1971	0.999930024147034
1972	0.999430000782013
1973	1.01310002803802
1974	0.989780008792877
1975	0.985419988632202
1976	0.986299991607666
1977	0.986240029335022
1978	1.06588995456696
1979	0.982060015201569
1980	0.991770029067993
1981	0.981509983539581
1983	0.987139999866486
1984	0.987619996070862
1985	0.989289999008179
1986	0.990490019321442
1987	0.987360000610352
1988	0.98487001657486
1989	0.984139978885651
1990	0.987789988517761
1991	0.98716002702713
1992	0.984790027141571
1993	0.985859990119934
1994	0.985300004482269
1995	0.985319972038269
1996	0.987810015678406
1997	0.987479984760284
1998	0.987980008125305
1999	0.986140012741089
2000	0.983299970626831
2001	0.978559970855713
2002	0.977419972419739
2003	0.975470006465912
2004	0.973190009593964
2005	0.974839985370636
2006	0.972039997577667
2007	0.97121000289917
2008	0.968429982662201
2009	0.965740025043488
2010	0.967599987983704
2011	0.970390021800995
2012	0.971840023994446
2013	0.974470019340515
2014	0.977810025215149
2015	0.978380024433136
2016	0.978829979896545
2017	0.983910024166107
2018	0.990429997444153
2019	0.994599997997284
2020	0.9896399974823