Year	gross (GPI)
1971	0.531180024147034
1972	0.544359982013702
1973	0.563289999961853
1974	0.574100017547607
1975	0.579789996147156
1976	0.584879994392395
1977	0.586409986019135
1978	0.592429995536804
1979	0.598699986934662
1980	0.602840006351471
1981	0.612779974937439
1982	0.622470021247864
1983	0.631410002708435
1984	0.628880023956299
1985	0.635959982872009
1986	0.643899977207184
1987	0.648159980773926
1988	0.655210018157959
1989	0.663450002670288
1990	0.677209973335266
1991	0.688260018825531
1992	0.698199987411499
1993	0.708540022373199
1994	0.725000023841858
1995	0.7396399974823
1996	0.753949999809265
1997	0.766820013523102
1998	0.786899983882904
1999	0.820620000362396
2000	0.849709987640381
2001	0.878610014915466
2002	0.896780014038086
2003	0.907909989356995
2004	0.910449981689453
2005	0.907310009002686
2006	0.905759990215302
2007	0.911220014095306
2008	0.919149994850159
2009	0.931810021400452
2010	0.940720021724701
2011	0.948390007019043
2012	0.953329980373383
2013	0.95592999458313
2014	0.95608001947403
2015	0.950020015239716
2016	0.954039990901947
2017	0.955569982528687
2018	0.960389971733093
2019	0.966050028800964
2020	0.970459997653961
2021	0.972779989242554