Year	gross (GPI)
1970	0.922760009765625
1971	0.919719994068146
1972	0.930980026721954
1973	0.929050028324127
1974	0.937799990177155
1975	0.939159989356995
1976	0.936800003051758
1977	0.939059972763062
1978	0.942260026931763
1979	0.942809998989105
1980	0.945890009403229
1981	0.94744998216629
1982	0.94515997171402
1983	0.94419002532959
1984	0.947700023651123
1985	0.95209002494812
1986	0.957639992237091
1987	0.961839973926544
1988	0.965070009231567
1989	0.971989989280701
1990	0.971530020236969
1991	0.975430011749268
1992	0.972859978675842
1993	0.975740015506744
1994	0.975380003452301
1995	0.978940010070801
1996	0.979189991950989
1997	0.979809999465942
1998	0.975870013237
1999	0.969910025596619
2000	0.969749987125397
2001	0.970770001411438
2002	0.97105997800827
2003	0.97351998090744
2004	0.97613000869751
2005	0.978219985961914
2006	0.977129995822906
2007	0.975300014019012
2008	0.974250018596649
2009	0.974399983882904
2010	0.96763002872467
2011	0.969839990139008
2012	0.974940001964569
2013	0.971561312675476
2014	0.971962571144104
2015	0.969376385211945