Year	gross (GPI)
1981	0.263960003852844
1987	0.411949992179871
1988	0.428039997816086
1989	0.437590003013611
1990	0.451440006494522
1991	0.476179987192154
1992	0.515200018882751
1993	0.510290026664734
1994	0.559300005435944
1995	0.574159979820251
1996	0.516969978809357
1997	0.540809988975525
1998	0.719900012016296
1999	0.71833997964859
2000	0.735759973526001
2001	0.773299992084503
2002	0.782079994678497
2003	0.825010001659393
2004	0.854839980602264
2005	0.875630021095276
2006	0.843410015106201
2008	0.881340026855469
2009	0.837819993495941
2010	0.852429986000061
2011	0.846109986305237
2012	0.846530020236969
2013	0.937510013580322
2014	0.915300011634827
2015	0.930079996585846
2016	0.971610009670258
2017	1.00393998622894
2018	1.01653003692627
2019	1.05332005023956
2020	1.06531000137329