Year	gross (GPI)
1970	0.751810014247894
1971	0.751429975032806
1972	0.751829981803894
1973	0.751470029354095
1974	0.752439975738525
1975	0.779579997062683
1976	0.793070018291473
1977	0.796890020370483
1978	0.799589991569519
1979	0.803430020809174
1980	0.802479982376099
1981	0.800289988517761
1982	0.798290014266968
1983	0.800660014152527
1984	0.800819993019104
1985	0.802739977836609
1986	0.820070028305054
1987	0.828149974346161
1988	0.832930028438568
1989	0.837549984455109
1990	0.842400014400482
1991	0.850690007209778
1992	0.857739984989166
1993	0.86369001865387
1994	0.872359991073608
1995	0.877740025520325
1996	0.882499992847443
1997	0.889859974384308
1998	0.896960020065308
1999	0.904799997806549
2000	0.908190011978149
2001	0.911979973316193
2002	0.91541999578476
2003	0.935429990291595
2004	0.936850011348724
2005	0.942349970340729
2006	0.946979999542236
2007	0.95194000005722
2008	0.959980010986328
2009	0.967920005321503
2010	0.967270016670227
2011	0.970120012760162
2012	0.974259972572327
2013	0.990509986877441
2014	0.992699980735779
2015	0.993640005588531
2016	0.999930024147034
2017	0.998300015926361
2018	0.98513001203537
2019	0.986320018768311
2020	0.983709990978241