Year	gross (GPI)
1970	0.712740004062653
1971	0.718590021133423
1972	0.728399991989136
1973	0.736379981040955
1974	0.747099995613098
1975	0.751630008220673
1976	0.753489971160889
1977	0.769050002098084
1978	0.781490027904511
1979	0.78627997636795
1980	0.797900021076202
1981	0.807699978351593
1982	0.808809995651245
1983	0.807609975337982
1984	0.812510013580322
1985	0.815490007400513
1986	0.821009993553162
1987	0.832090020179749
1988	0.813539981842041
1989	0.840309977531433
1990	0.830550014972687
1991	0.837970018386841
1992	0.843349993228912
1993	0.84290999174118
1994	0.844690024852753
1995	0.839489996433258
1996	0.842570006847382
1997	0.841539978981018
1998	0.838580012321472
1999	0.847010016441345
2000	0.851119995117188
2001	0.85835999250412
2002	0.857640027999878
2003	0.865190029144287
2004	0.873059988021851
2005	0.882309973239899
2006	0.894309997558594
2007	0.903609991073608
2008	0.910719990730286
2009	0.918850004673004
2010	0.924719989299774
2011	0.922980010509491
2012	0.936609983444214
2013	0.943859994411469
2014	0.949919998645782
2015	0.956130027770996
2016	0.954039990901947
2017	0.956229984760284
2018	0.957340002059937
2019	0.957449972629547
2020	0.957690000534058