Year	gross (GPI)
1970	0.570840001106262
1971	0.570249974727631
1972	0.578980028629303
1973	0.589190006256104
1974	0.596909999847412
1975	0.607439994812012
1976	0.621619999408722
1977	0.636280000209808
1978	0.648540019989014
1979	0.671230018138886
1980	0.684970021247864
1981	0.699150025844574
1982	0.71085000038147
1983	0.723200023174286
1984	0.736790001392365
1985	0.74974000453949
1986	0.760370016098022
1987	0.767390012741089
1988	0.771200001239777
1989	0.784449994564056
1990	0.797619998455048
1991	0.809430003166199
1992	0.823939979076386
1993	0.833329975605011
1994	0.837629973888397
1995	0.852029979228973
1996	0.840210020542145
1997	0.863529980182648
1998	0.873520016670227
1999	0.884809970855713
2000	0.893389999866486
2001	0.900319993495941
2002	0.906819999217987
2003	0.913420021533966
2004	0.918489992618561
2005	0.922609984874725
2006	0.927240014076233
2007	0.936280012130737
2008	0.934010028839111
2009	0.934069991111755
2010	0.935109972953796
2011	0.933780014514923
2012	0.93844997882843
2013	0.943899989128113
2014	0.950929999351501
2015	0.953220009803772
2016	0.956990003585815
2017	0.956889986991882
2018	0.959659993648529
2019	0.962660014629364
2020	0.965900003910065