Year	gross (GPI)
1970	0.596769988536835
1971	0.610440015792847
1972	0.625320017337799
1973	0.643369972705841
1974	0.654770016670227
1975	0.662919998168945
1976	0.671370029449463
1977	0.688610017299652
1978	0.738829970359802
1979	0.746290028095245
1980	0.761650025844574
1981	0.772610008716583
1982	0.774119973182678
1983	0.76366001367569
1984	0.765550017356873
1985	0.779850006103516
1986	0.784169971942902
1987	0.780470013618469
1988	0.758979976177216
1989	0.787989974021912
1990	0.766070008277893
1991	0.77591997385025
1992	0.786080002784729
1993	0.784929990768433
1994	0.790499985218048
1995	0.796230018138886
1996	0.807179987430573
1997	0.807630002498627
1998	0.803699970245361
1999	0.800140023231506
2000	0.809509992599487
2001	0.817399978637695
2002	0.812129974365234
2003	0.831550002098084
2004	0.833000004291534
2005	0.845929980278015
2006	0.862100005149841
2007	0.887070000171661
2008	0.892220020294189
2009	0.899649977684021
2010	0.905059993267059
2011	0.919960021972656
2012	0.943859994411469
2013	0.9444500207901
2014	0.9410799741745
2015	0.936360001564026
2016	0.921829998493195
2017	0.932210028171539
2018	0.931670010089874
2019	0.9376500248909
2020	0.931770026683807