Year	gross (GPI)
1971	0.24422000348568
1972	0.261330008506775
1973	0.333070009946823
1974	0.390450000762939
1975	0.420049995183945
1976	0.430310010910034
1977	0.476300001144409
1978	0.458920001983643
1979	0.463609993457794
1980	0.470699995756149
1981	0.460700005292892
1982	0.563359975814819
1983	0.47257998585701
1984	0.476889997720718
1985	0.505559980869293
1986	0.492830008268356
1987	0.537129998207092
1988	0.554270029067993
1989	0.580209970474243
1990	0.606639981269836
1991	0.571460008621216
1992	0.597590029239655
1993	0.623000025749207
2003	0.767970025539398
2004	0.752229988574982
2005	0.737209975719452
2006	0.737600028514862
2007	0.717890024185181
2009	0.720420002937317
2010	0.716629981994629
2011	0.73539000749588
2012	0.762629985809326
2013	0.811450004577637
2014	0.874430000782013
2015	0.936649978160858
2016	0.994859993457794
2017	1.04894995689392
2018	1.11448001861572
2019	1.15231001377106
2020	1.21476995944977