Year	gross (GPI)
1970	0.606880009174347
1971	0.605939984321594
1972	0.614160001277924
1973	0.623409986495972
1974	0.629840016365051
1975	0.642870008945465
1976	0.656189978122711
1977	0.670930027961731
1978	0.684790015220642
1979	0.712790012359619
1980	0.727419972419739
1981	0.741209983825684
1982	0.75094997882843
1983	0.760810017585754
1984	0.77455997467041
1985	0.787590026855469
1986	0.800530016422272
1987	0.809729993343353
1988	0.812080025672913
1989	0.827180027961731
1990	0.837170004844666
1991	0.841009974479675
1992	0.852100014686584
1993	0.857659995555878
1994	0.859070003032684
1995	0.867720007896423
1996	0.840789973735809
1997	0.869009971618652
1998	0.875699996948242
1999	0.883469998836517
2000	0.89096999168396
2001	0.8994500041008
2002	0.906369984149933
2003	0.911180019378662
2004	0.914479970932007
2005	0.915160000324249
2006	0.91746997833252
2007	0.923349976539612
2008	0.927940011024475
2009	0.930519998073578
2010	0.932510018348694
2011	0.928399980068207
2012	0.939419984817505
2013	0.950219988822937
2014	0.958720028400421
2015	0.962360024452209
2016	0.966040015220642
2017	0.964810013771057
2018	0.965929985046387
2019	0.967899978160858
2020	0.970470011234283