Year	gross (GPI)
1970	0.754159986972809
1971	0.755900025367737
1972	0.763979971408844
1973	0.769689977169037
1974	0.78150999546051
1975	0.787519991397858
1976	0.787140011787415
1977	0.796869993209839
1978	0.809080004692078
1979	0.816200017929077
1980	0.828809976577759
1981	0.841509997844696
1982	0.847779989242554
1983	0.851339995861053
1984	0.85835999250412
1985	0.851549983024597
1986	0.85563999414444
1987	0.874490022659302
1988	0.864419996738434
1989	0.876269996166229
1990	0.881669998168945
1991	0.885259985923767
1992	0.886979997158051
1993	0.891889989376068
1994	0.889569997787476
1995	0.871230006217957
1996	0.867380023002625
1997	0.867470026016235
1998	0.86625999212265
1999	0.884970009326935
2000	0.885129988193512
2001	0.888729989528656
2002	0.886640012264252
2003	0.891460001468658
2004	0.899609982967377
2005	0.90896999835968
2006	0.91907000541687
2007	0.921670019626617
2008	0.927680015563965
2009	0.936850011348724
2010	0.940020024776459
2011	0.927760004997253
2012	0.935400009155273
2013	0.944930016994476
2014	0.95074999332428
2015	0.961650013923645
2016	0.964749991893768
2017	0.962369978427887
2018	0.958050012588501
2019	0.960449993610382
2020	0.962589979171753