Year	gross (GPI)
1970	0.608299970626831
1971	0.613610029220581
1972	0.623570024967194
1973	0.633270025253296
1974	0.646570026874542
1975	0.653050005435944
1976	0.657299995422363
1977	0.67901998758316
1978	0.696780025959015
1979	0.710870027542114
1980	0.72105997800827
1981	0.731809973716736
1982	0.749979972839355
1983	0.736840009689331
1984	0.730849981307983
1985	0.743480026721954
1986	0.763400018215179
1987	0.778509974479675
1988	0.763040006160736
1989	0.781599998474121
1990	0.771690011024475
1991	0.780059993267059
1992	0.781229972839355
1993	0.780520021915436
1994	0.7846599817276
1995	0.787090003490448
1996	0.790970027446747
1997	0.794390022754669
1998	0.792519986629486
1999	0.80062997341156
2000	0.80333000421524
2001	0.807290017604828
2002	0.804350018501282
2003	0.817879974842072
2004	0.810350000858307
2005	0.827160000801086
2006	0.834249973297119
2007	0.838680028915405
2008	0.847869992256165
2009	0.85632997751236
2010	0.863300025463104
2011	0.865400016307831
2012	0.881269991397858
2013	0.889540016651154
2014	0.893750011920929
2015	0.903609991073608
2016	0.901019990444183
2017	0.906710028648376
2018	0.910749971866608
2019	0.911300003528595