Year	gross (GPI)
1970	0.721859991550446
1971	0.722899973392487
1972	0.724380016326904
1973	0.725679993629456
1974	0.733650028705597
1975	0.740620017051697
1976	0.740809977054596
1977	0.744379997253418
1978	0.757929980754852
1979	0.770969986915588
1980	0.761820018291473
1981	0.751919984817505
1982	0.747319996356964
1983	0.760330021381378
1984	0.749870002269745
1985	0.741490006446838
1986	0.767859995365143
1987	0.780059993267059
1988	0.78643000125885
1989	0.794990003108978
1990	0.798699975013733
1991	0.805800020694733
1992	0.81427001953125
1993	0.820860028266907
1994	0.839200019836426
1995	0.84918999671936
1996	0.858900010585785
1997	0.871399998664856
1998	0.888140022754669
1999	0.902980029582977
2000	0.90871000289917
2001	0.912490010261536
2002	0.918690025806427
2003	0.936060011386871
2004	0.93870997428894
2005	0.948379993438721
2006	0.955229997634888
2007	0.962949991226196
2008	0.972150027751923
2009	0.98514997959137
2010	0.978559970855713
2011	0.981970012187958
2012	0.985450029373169
2013	0.998939990997314
2014	1.00468003749847
2015	1.00370001792908
2016	1.0064400434494
2017	1.00522994995117
2018	1.00854003429413
2019	1.01047003269196
2020	1.00469994544983