Year	gross (GPI)
1972	0.957159996032715
1973	0.951399981975555
1974	0.948310017585754
1975	0.944920003414154
1978	0.960550010204315
1979	0.970560014247894
1980	0.967970013618469
1981	0.974520027637482
1982	0.980599999427795
1983	0.99125999212265
1984	0.983219981193542
1985	0.983579993247986
1986	0.99466997385025
1987	0.998220026493073
1988	1.0113799571991
1989	1.03287994861603
1990	1.04846000671387
1991	1.06269001960754
1992	1.07169997692108
1993	1.05492997169495
1994	1.04086995124817
1995	1.04086005687714
1996	0.994040012359619
1997	1.01600003242493
1999	0.995000004768372
2000	0.988499999046326
2001	0.993399977684021
2002	0.971939980983734
2003	0.971340000629425
2004	0.989419996738434
2005	0.994029998779297
2006	0.999710023403168
2007	0.992500007152557
2008	0.991890013217926
2009	0.992110013961792
2010	0.989660024642944
2011	0.989809989929199
2012	0.997210025787354
2013	0.992250025272369
2014	0.982819974422455
2015	0.985199987888336
2016	0.991129994392395
2017	0.98496001958847
2018	0.986819982528687
2019	0.988439977169037
2020	0.988740026950836
2021	1.00246000289917