Year	gross (GPI)
1970	0.924369990825653
1971	0.949720025062561
1972	0.965569972991943
1973	0.965799987316132
1974	0.98089998960495
1975	1.03104996681213
1976	1.03200995922089
1977	1.00478994846344
1978	1.01285004615784
1979	1.0351300239563
1980	1.03235995769501
1981	1.04198002815247
1982	1.0396900177002
1983	1.04289996623993
1984	1.03864002227783
1985	1.01412999629974
1986	1.04103004932404
1987	1.041100025177
1988	1.04425001144409
1989	1.04867005348206
1990	1.05727994441986
1991	1.06650996208191
1992	1.06234002113342
1993	1.06301999092102
1994	1.06340003013611
1995	1.06431996822357
1996	1.05552995204926
1997	1.05847001075745
1998	1.06011998653412
1999	1.05540001392365
2000	1.06234002113342
2001	1.05762004852295
2002	1.05704998970032
2003	1.07483005523682
2004	1.07082998752594
2005	1.07306003570557
2006	1.07440996170044
2007	1.09145998954773
2008	1.09598994255066
2009	1.09251999855042
2010	1.08241999149323
2011	1.0791300535202
2012	1.06708002090454
2013	1.0584100484848
2014	1.05833995342255
2015	1.05474996566772
2016	1.04797995090485
2017	1.04146003723145
2018	1.04370999336243
2019	1.04849004745483
2020	1.05157995223999