Year	gross (GPI)
1970	0.970399975776672
1971	0.946709990501404
1972	0.948859989643097
1973	0.946420013904572
1974	0.94582998752594
1975	0.945100009441376
1976	0.943889975547791
1977	0.955649971961975
1978	0.955060005187988
1979	0.960319995880127
1980	0.951219975948334
1981	0.96959000825882
1982	0.982200026512146
1983	0.975730001926422
1984	0.968259990215302
1986	0.977859973907471
1987	0.955460011959076
1988	0.972039997577667
1989	0.959200024604797
1991	0.944719970226288
1992	0.955349981784821
1993	0.968479990959167
1994	0.963249981403351
1995	0.949750006198883
1996	0.953559994697571
1997	0.943130016326904
1998	0.936760008335114
1999	0.929920017719269
2000	0.948059976100922
2001	0.954500019550323
2002	0.964680016040802
2003	0.975369989871979
2004	0.966409981250763
2005	0.961510002613068
2006	0.953180015087128
2007	0.956939995288849
2008	0.972259998321533
2009	0.98633998632431
2010	0.995639204978943
2011	1.00647282600403
2012	0.991123855113983
2013	0.99665355682373
2014	1.00075507164001
2015	0.996651291847229
2016	0.998992621898651
2017	1.00008738040924
2018	1.0083624124527
2019	1.00834703445435
2020	1.00382149219513