Year	gross (GPI)
1970	0.621169984340668
1971	0.638360023498535
1972	0.654070019721985
1973	0.667630016803741
1974	0.672529995441437
1975	0.672869980335236
1976	0.678520023822784
1977	0.711880028247833
1978	0.731769979000092
1979	0.736459970474243
1980	0.746980011463165
1981	0.754589974880219
1982	0.751980006694794
1983	0.745299994945526
1984	0.747919976711273
1985	0.764739990234375
1986	0.768450021743774
1987	0.768239974975586
1988	0.736599981784821
1989	0.782909989356995
1990	0.754960000514984
1991	0.766290009021759
1992	0.779950022697449
1993	0.77403998374939
1994	0.781390011310577
1995	0.791499972343445
1996	0.801680028438568
1997	0.798609972000122
1998	0.794550001621246
1999	0.790910005569458
2000	0.80171000957489
2001	0.812789976596832
2002	0.81370997428894
2003	0.823650002479553
2004	0.831120014190674
2005	0.839049994945526
2006	0.853349983692169
2007	0.870519995689392
2008	0.877070009708405
2009	0.884580016136169
2010	0.896009981632233
2011	0.913609981536865
2012	0.937669992446899
2013	0.941259980201721
2014	0.947510004043579
2015	0.945710003376007
2016	0.93488997220993
2017	0.944719970226288
2018	0.954940021038055
2019	0.950869977474213
2020	0.947369992733002