Year	gross (GPI)
1970	0.758109986782074
1971	0.759419977664948
1972	0.765359997749329
1973	0.770550012588501
1974	0.78125
1975	0.784210026264191
1976	0.782580018043518
1977	0.789420008659363
1978	0.797399997711182
1979	0.801649987697601
1980	0.811909973621368
1981	0.821569979190826
1982	0.826870024204254
1983	0.830320000648499
1984	0.836009979248047
1985	0.831470012664795
1986	0.836849987506866
1987	0.853290021419525
1988	0.847940027713776
1989	0.860490024089813
1990	0.870360016822815
1991	0.874729990959167
1992	0.878069996833801
1993	0.882049977779388
1994	0.87907999753952
1995	0.869859993457794
1996	0.867079973220825
1997	0.866699993610382
1998	0.86515998840332
1999	0.877820014953613
2000	0.875769972801209
2001	0.876429975032806
2002	0.874459981918335
2003	0.877120018005371
2004	0.880230009555817
2005	0.887009978294373
2006	0.893890023231506
2007	0.894240021705627
2008	0.90158998966217
2009	0.9096400141716
2010	0.914219975471497
2011	0.908349990844727
2012	0.915709972381592
2013	0.926739990711212
2014	0.932219982147217
2015	0.939180016517639
2016	0.944530010223389
2017	0.943430006504059
2018	0.940410017967224
2019	0.941209971904755
2020	0.944029986858368