Year	gross (GPI)
1970	0.602199971675873
1971	0.605589985847473
1972	0.620440006256104
1973	0.625310003757477
1974	0.628279983997345
1975	0.63400000333786
1976	0.640139997005463
1977	0.654020011425018
1978	0.672010004520416
1979	0.678770005702972
1980	0.688730001449585
1981	0.702740013599396
1982	0.71696001291275
1983	0.701610028743744
1984	0.710169970989227
1985	0.718729972839355
1986	0.734920024871826
1987	0.740490019321442
1988	0.743600010871887
1989	0.75543999671936
1990	0.754239976406097
1991	0.765209972858429
1992	0.772740006446838
1993	0.777610003948212
1994	0.783779978752136
1995	0.789030015468597
1996	0.796220004558563
1997	0.80418998003006
1998	0.80961000919342
1999	0.820959985256195
2000	0.829180002212524
2001	0.835979998111725
2002	0.836839973926544
2003	0.849319994449615
2004	0.844739973545074
2005	0.863210022449493
2006	0.873000025749207
2007	0.880659997463226
2008	0.89069002866745
2009	0.898630023002625
2010	0.907270014286041
2011	0.914260029792786
2012	0.923340022563934
2013	0.92467999458313
2014	0.928550004959106
2015	0.935079991817474
2016	0.933480024337769
2017	0.93911999464035
2018	0.941120028495789
2019	0.944500029087067
2020	0.946439981460571