Year	gross (GPI)
1970	0.734170019626617
1971	0.757539987564087
1972	0.77114999294281
1973	0.791899979114532
1974	0.830680012702942
1975	0.860589981079102
1976	0.878419995307922
1977	0.887740015983582
1978	0.894299983978271
1979	0.907899975776672
1980	0.921989977359772
1981	0.933780014514923
1982	0.941120028495789
1983	0.941219985485077
1984	0.950219988822937
1985	0.956659972667694
1986	0.952719986438751
1987	0.955420017242432
1988	0.965579986572266
1989	0.962750017642975
1990	0.96587997674942
1991	0.970709979534149
1992	0.970459997653961
1993	0.977840006351471
1994	0.984329998493195
1995	0.981630027294159
1998	0.977259993553162
1999	0.967689990997314
2000	0.98157000541687
2001	0.975830018520355
2002	0.945029973983765
2003	0.948210000991821
2004	0.939689993858337
2005	0.956709980964661
2006	0.969519972801209
2007	0.983500003814697
2008	0.978240013122559
2009	0.977930009365082
2012	1.00824999809265
2014	1.00738000869751
2015	0.999469995498657
2016	1.00370001792908
2019	0.970903754234314