Year	gross (GPI)
1970	0.963209986686707
1971	0.965870022773743
1972	0.961960017681122
1973	0.967429995536804
1974	0.974590003490448
1975	0.983039975166321
1976	0.984759986400604
1977	0.982959985733032
1978	0.984430015087128
1979	0.998120009899139
1980	1.00042998790741
1981	1.00317001342773
1982	1.00111997127533
1983	1.00088000297546
1984	0.999189972877502
1985	0.989740014076233
1986	1.00338995456696
1987	1.00574004650116
1988	1.01038002967834
1989	1.01216995716095
1990	1.01675999164581
1991	1.01569998264313
1992	1.01442003250122
1993	1.01285004615784
1994	1.01058995723724
1995	1.00938999652863
1996	1.00574994087219
1997	1.0074599981308
1998	1.0069500207901
1999	1.00924003124237
2000	1.01084005832672
2001	1.00893998146057
2002	1.00855004787445
2003	1.01740002632141
2004	1.01645004749298
2005	1.01575005054474
2006	1.0174800157547
2007	1.02534997463226
2008	1.02595996856689
2009	1.02735996246338
2010	1.02125000953674
2011	1.02011001110077
2012	1.018630027771
2013	1.01582002639771
2014	1.01590001583099
2015	1.01611995697021
2016	1.01408004760742
2017	1.01257002353668
2018	1.01449000835419
2019	1.01665997505188
2020	1.01661002635956