Year	gross (GPI)
1970	0.512210011482239
1971	0.511730015277863
1972	0.526359975337982
1973	0.538779973983765
1974	0.551859974861145
1975	0.557420015335083
1976	0.573769986629486
1977	0.588890016078949
1978	0.59987998008728
1979	0.61379998922348
1980	0.624509990215302
1981	0.639729976654053
1982	0.654670000076294
1983	0.670300006866455
1984	0.682640016078949
1985	0.695609986782074
1986	0.703199982643127
1987	0.70974999666214
1988	0.717599987983704
1989	0.727980017662048
1990	0.748690009117126
1991	0.768639981746674
1992	0.78711998462677
1993	0.802739977836609
1994	0.812479972839355
1995	0.835759997367859
1996	0.848089993000031
1997	0.864690005779266
1998	0.87907999753952
1999	0.893760025501251
2000	0.903439998626709
2001	0.909039974212646
2002	0.915180027484894
2003	0.92315000295639
2004	0.930350005626678
2005	0.939140021800995
2006	0.945179998874664
2007	0.957019984722137
2008	0.947210013866425
2009	0.942369997501373
2010	0.942369997501373
2011	0.9444500207901
2012	0.945590019226074
2013	0.946709990501404
2014	0.951449990272522
2015	0.952400028705597
2016	0.950010001659393
2017	0.949060022830963
2018	0.957750022411346
2019	0.958450019359589
2020	0.964619994163513