Year	gross (GPI)
1970	0.579219996929169
1971	0.582490026950836
1972	0.586759984493256
1973	0.593230009078979
1974	0.600470006465912
1975	0.608690023422241
1976	0.614950001239777
1977	0.614019989967346
1978	0.619490027427673
1979	0.623019993305206
1980	0.624430000782013
1981	0.62788999080658
1982	0.624970018863678
1983	0.649060010910034
1984	0.626959979534149
1985	0.642159998416901
1986	0.660629987716675
1987	0.670610010623932
1988	0.679409980773926
1989	0.689360022544861
1990	0.698409974575043
1991	0.707679986953735
1992	0.718020021915436
1993	0.727720022201538
1994	0.745720028877258
1995	0.756429970264435
1996	0.767690002918243
1997	0.788999974727631
1998	0.811010003089905
1999	0.832180023193359
2000	0.838559985160828
2001	0.845220029354095
2002	0.85698002576828
2003	0.887880027294159
2004	0.885330021381378
2005	0.894749999046326
2006	0.902559995651245
2007	0.912580013275146
2008	0.924319982528687
2009	0.942960023880005
2010	0.947359979152679
2011	0.953610002994537
2012	0.960080027580261
2013	0.979879975318909
2014	0.988020002841949
2015	0.990710020065308
2016	0.99550998210907
2017	0.997160017490387
2018	1.00181996822357
2019	1.00541996955872
2020	0.996580004692078