Year	gross (GPI)
1971	0.901139974594116
1976	0.889810025691986
1981	0.89766001701355
1982	0.911849975585938
1983	0.90513002872467
1984	0.905539989471436
1985	0.92765998840332
1986	0.912199974060059
1987	0.902570009231567
1988	0.90912002325058
1989	0.923259973526001
1990	0.914640009403229
1991	0.922699987888336
1992	0.923500001430511
1993	0.930400013923645
1994	0.93682998418808
1995	0.939140021800995
1996	0.945230007171631
1997	0.953400015830994
1998	0.945990025997162
1999	0.954739987850189
2000	0.959370017051697
2001	0.959190011024475
2002	0.951460003852844
2003	0.948480010032654
2004	0.944930016994476
2005	0.951629996299744
2006	0.960089981555939
2007	0.960520029067993
2008	0.957889974117279
2009	0.955129981040955
2010	0.960730016231537
2011	0.961000025272369
2012	0.962430000305176
2013	0.965590000152588
2014	0.962480008602142
2015	0.964339971542358
2016	0.961210012435913
2017	0.959550023078918
2018	0.964039981365204
2019	0.974910020828247
2020	0.981540024280548