Year	gross (GPI)
1970	0.643800020217896
1971	0.642799973487854
1972	0.648909986019135
1973	0.652199983596802
1974	0.657949984073639
1975	0.657739996910095
1976	0.657890021800995
1977	0.66566002368927
1978	0.671429991722107
1979	0.672110021114349
1980	0.681450009346008
1981	0.689239978790283
1982	0.715870022773743
1983	0.718249976634979
1984	0.723699986934662
1985	0.717100024223328
1986	0.723420023918152
1987	0.73733001947403
1988	0.728079974651337
1989	0.732649981975555
1990	0.734189987182617
1991	0.741720020771027
1992	0.741569995880127
1993	0.742699980735779
1994	0.738359987735748
1995	0.734160006046295
1996	0.727240025997162
1997	0.732810020446777
1998	0.732999980449677
1999	0.749409973621368
2000	0.758819997310638
2001	0.764050006866455
2002	0.772040009498596
2003	0.783270001411438
2004	0.778880000114441
2005	0.805610001087189
2006	0.818009972572327
2007	0.824840009212494
2008	0.837180018424988
2009	0.848739981651306
2010	0.857580006122589
2011	0.865029990673065
2012	0.872179985046387
2013	0.878019988536835
2014	0.880699992179871
2015	0.89122998714447
2016	0.89301997423172
2017	0.894320011138916
2018	0.892610013484955
2019	0.894339978694916
2020	0.897710025310516