Year	gross (GPI)
1971	0.877659976482391
1972	0.880879998207092
1973	0.881309986114502
1974	0.882189989089966
1975	0.88384997844696
1976	0.885869979858398
1977	0.890120029449463
1978	0.898119986057281
1979	0.911239981651306
1980	0.9341099858284
1981	0.949150025844574
1982	0.954249978065491
1983	0.957340002059937
1984	0.966920018196106
1985	0.975149989128113
1986	0.980650007724762
1987	0.993350028991699
1988	0.977859973907471
1989	0.980430006980896
1990	0.983640015125275
1991	0.987950026988983
1992	0.991810023784637
1993	0.997669994831085
1994	0.997359991073608
1995	1.01213002204895
1996	1.01521003246307
1997	1.01029002666473
1998	1.01148998737335
1999	1.00989997386932
2000	1.00961005687714
2001	1.01021003723145
2002	1.00986003875732
2003	1.00964999198914
2004	1.00923001766205
2005	1.00725996494293
2006	1.0020500421524
2007	0.999469995498657
2008	0.99906998872757
2009	0.998329997062683
2010	0.997699975967407
2011	0.996860027313232
2012	0.997269988059998
2013	0.997399985790253
2014	0.996720016002655
2015	0.995540022850037
2016	0.99481999874115
2017	0.995310008525848
2018	0.995530009269714
2019	0.9964200258255
2020	0.9964200258255