Year	gross (GPI)
1970	0.607869982719421
1971	0.609179973602295
1972	0.615939974784851
1973	0.622630000114441
1974	0.617470026016235
1975	0.620700001716614
1976	0.626320004463196
1977	0.634310007095337
1978	0.632470011711121
1979	0.642620027065277
1980	0.647040009498596
1981	0.660080015659332
1982	0.667429983615875
1983	0.663290023803711
1984	0.675080001354218
1985	0.687940001487732
1986	0.706709980964661
1987	0.715659976005554
1988	0.732649981975555
1989	0.722469985485077
1990	0.736959993839264
1991	0.759299993515015
1992	0.770529985427856
1993	0.796480000019073
1994	0.806949973106384
1995	0.810620009899139
1996	0.819490015506744
1997	0.827400028705597
1998	0.833270013332367
1999	0.837989985942841
2000	0.844389975070953
2001	0.853290021419525
2002	0.866599977016449
2003	0.947239995002747
2004	0.94284999370575
2005	0.95550000667572
2006	0.96315997838974
2007	0.969749987125397
2008	0.990440011024475
2009	1.00128996372223
2010	1.00032997131348
2011	1.00873994827271
2012	1.01263999938965
2013	1.06814002990723
2014	1.06050002574921
2015	1.06114995479584
2016	1.09157001972198
2017	1.08159005641937
2018	0.987129986286163
2019	0.991119980812073
2020	0.99098002910614