Year	gross (GPI)
1971	0.501429975032806
1972	0.516460001468658
1974	0.552510023117065
1975	0.558440029621124
1976	0.572889983654022
1977	0.579129993915558
1978	0.590969979763031
1979	0.601849973201752
1980	0.608690023422241
1981	0.618120014667511
1982	0.630890011787415
1983	0.643209993839264
1984	0.644869983196259
1985	0.650489985942841
1986	0.652379989624023
1987	0.656350016593933
1988	0.657890021800995
1989	0.662909984588623
1990	0.692330002784729
1991	0.700810015201569
1992	0.704779982566834
1993	0.714659988880157
1994	0.726769983768463
1995	0.740320026874542
1996	0.75084000825882
1997	0.761979997158051
1998	0.780399978160858
1999	0.808200001716614
2000	0.831789970397949
2001	0.854349970817566
2002	0.868110001087189
2003	0.879809975624084
2004	0.883870005607605
2005	0.886529982089996
2006	0.889819979667664
2007	0.895079970359802
2008	0.898289978504181
2009	0.905049979686737
2010	0.912400007247925
2011	0.91373997926712
2012	0.912949979305267
2017	0.930190026760101
2018	0.94147002696991
2019	0.951110005378723
2020	0.96220999956131
2021	0.971239984035492