Year	gross (GPI)
1970	0.616129994392395
1971	0.61531001329422
1972	0.622860014438629
1973	0.631229996681213
1974	0.636879980564117
1975	0.649030029773712
1976	0.661909997463226
1977	0.675890028476715
1978	0.688939988613129
1979	0.715489983558655
1980	0.729629993438721
1981	0.743070006370544
1982	0.752449989318848
1983	0.76214998960495
1984	0.775590002536774
1985	0.788370013237
1986	0.801090002059937
1987	0.810000002384186
1988	0.812990009784698
1989	0.827160000801086
1990	0.837090015411377
1991	0.840990006923676
1992	0.852689981460571
1993	0.859520018100739
1994	0.862039983272552
1995	0.87075001001358
1996	0.846449971199036
1997	0.872290015220642
1998	0.878809988498688
1999	0.886770009994507
2000	0.894990026950836
2001	0.904720008373261
2002	0.910960018634796
2003	0.91635000705719
2004	0.920880019664764
2005	0.92316997051239
2006	0.925660014152527
2007	0.930450022220612
2008	0.934530019760132
2009	0.936900019645691
2010	0.940150022506714
2011	0.936609983444214
2012	0.947380006313324
2013	0.95524001121521
2014	0.96246999502182
2015	0.969640016555786
2016	0.969539999961853
2017	0.969990015029907
2018	0.971369981765747
2019	0.973850011825562
2020	0.976170003414154