Year	gross (GPI)
1971	0.941670000553131
1972	0.946020007133484
1973	0.947459995746613
1974	0.94718998670578
1975	0.873740017414093
1976	0.936169981956482
1977	0.931869983673096
1978	0.942330002784729
1979	0.941009998321533
1982	0.955510020256042
1985	0.978309988975525
1986	0.971170008182526
1987	0.985960006713867
1988	0.988319993019104
1989	1.0083099603653
1990	1.10143995285034
1991	1.02401995658875
1992	1.01412999629974
1993	0.982299983501434
1994	1.04346001148224
2001	1.0081000328064
2002	0.991110026836395
2005	0.984319984912872
2006	0.992370009422302
2007	0.980700016021729
2008	1.00049996376038
2009	1.0011500120163
2010	0.996670007705688
2011	1.00103998184204
2012	0.99702000617981
2013	1.01486003398895
2014	1.01701998710632
2015	1.01013004779816
2016	1.00279998779297
2017	1.00379002094269
2018	0.997619986534119
2019	0.998709976673126
2020	0.999650001525879
2021	0.990209996700287