Year	gross (GPI)
1971	0.458409994840622
1972	0.466129988431931
1973	0.467220008373261
1974	0.47027999162674
1975	0.473580002784729
1976	0.477389991283417
1977	0.479999989271164
1978	0.492460012435913
1979	0.481020003557205
1980	0.531470000743866
1981	0.553399980068207
1982	0.574949979782104
1983	0.604179978370667
1984	0.621559977531433
1985	0.653859972953796
1986	0.657280027866364
1987	0.636810004711151
1988	0.62024998664856
1989	0.643220007419586
1990	0.656710028648376
1991	0.665549993515015
1992	0.727620005607605
1993	0.699410021305084
1994	0.629859983921051
1995	0.599179983139038
1996	0.57506000995636
1997	0.565310001373291
1998	0.589630007743835
1999	0.613669991493225
2000	0.656000018119812
2001	0.694159984588623
2002	0.717180013656616
2003	0.733839988708496
2004	0.782530009746552
2005	0.835560023784637
2006	0.872039973735809
2007	0.889339983463287
2008	0.904269993305206
2009	0.927230000495911
2010	0.924390017986298
2011	0.921130001544952
2012	0.928149998188019
2013	0.92558628320694
2014	0.917990028858185
2015	0.908510029315948
2016	0.907353699207306
2017	0.902628362178802
2018	0.900771856307983
2019	0.902289211750031
2020	0.902322709560394
2021	0.912419974803925