Year	gross (GPI)
1970	0.970420002937317
1971	0.970550000667572
1972	0.972190022468567
1973	0.975849986076355
1974	0.974979996681213
1975	0.976350009441376
1976	0.977630019187927
1977	0.979610025882721
1978	0.980499982833862
1979	0.981500029563904
1980	0.981599986553192
1981	0.982159972190857
1982	0.983980000019073
1983	0.985159993171692
1984	0.982640027999878
1985	0.983929991722107
1986	0.984650015830994
1987	0.985520005226135
1988	0.985960006713867
1989	0.988359987735748
1990	0.988049983978271
1991	0.9894700050354
1992	0.996810019016266
1993	0.989239990711212
1994	0.989459991455078
1995	0.991810023784637
1996	0.990899980068207
1997	0.985230028629303
1998	0.982800006866455
1999	0.98378998041153
2000	0.986639976501465
2001	0.987039983272552
2002	0.987950026988983
2003	0.988770008087158
2004	0.990220010280609
2005	0.990199983119965
2006	0.991360008716583
2007	0.991249978542328
2008	0.989600002765656
2009	0.990279972553253
2010	0.991199970245361
2011	0.993040025234222
2012	0.995980024337769
2013	0.995729982852936
2014	0.996299982070923
2015	0.997730016708374
2016	0.998390018939972
2017	0.997789978981018
2018	0.993669986724854
2019	0.991919994354248
2020	0.984780013561249