Year	gross (GPI)
1971	0.907029986381531
1972	0.935079991817474
1973	0.953130006790161
1974	0.978600025177002
1975	0.93614000082016
1976	0.954150021076202
1977	0.956990003585815
1978	0.973179996013641
1979	0.988219976425171
1980	1.0095100402832
1981	1.0159900188446
1982	1.03419995307922
1983	1.05209994316101
1984	1.0512900352478
1985	1.0474499464035
1986	1.04078996181488
1987	1.05338001251221
1988	1.04849004745483
1989	1.04057002067566
1990	1.02937996387482
1991	1.03190994262695
1992	1.03863000869751
1993	1.02192997932434
1994	1.01437997817993
1995	1.01199996471405
1996	1.02216005325317
1997	1.02402997016907
1999	1.03109002113342
2000	1.02259004116058
2001	1.00957000255585
2002	1.02155995368958
2003	1.01693999767303
2004	1.02743005752563
2005	1.01907002925873
2006	1.01705002784729
2007	1.01844000816345
2008	1.01113998889923
2009	1.01315999031067
2010	1.01189994812012
2011	1.01495003700256
2012	1.0183299779892
2013	1.00426995754242
2014	1.00076997280121
2015	0.99277001619339
2016	0.986299991607666
2017	0.984399974346161
2018	0.975019991397858
2019	0.968739986419678
2020	0.969479978084564