Year	gross (GPI)
1970	0.468439996242523
1971	0.468690007925034
1972	0.488779991865158
1973	0.503589987754822
1974	0.517910003662109
1975	0.525569975376129
1976	0.544679999351501
1977	0.5625
1978	0.576520025730133
1979	0.592270016670227
1980	0.603550016880035
1981	0.62033998966217
1982	0.635990023612976
1983	0.652700006961823
1984	0.665700018405914
1985	0.679480016231537
1986	0.687659978866577
1987	0.69242000579834
1988	0.699479997158051
1989	0.709789991378784
1990	0.733410000801086
1991	0.755400002002716
1992	0.776049971580505
1993	0.792869985103607
1994	0.803439974784851
1995	0.828400015830994
1996	0.840730011463165
1997	0.857649981975555
1998	0.873059988021851
1999	0.889339983463287
2000	0.899119973182678
2001	0.903819978237152
2002	0.909609973430634
2003	0.917919993400574
2004	0.924700021743774
2005	0.933070003986359
2006	0.940680027008057
2007	0.954150021076202
2008	0.943459987640381
2009	0.940410017967224
2010	0.940159976482391
2011	0.941980004310608
2012	0.938929975032806
2013	0.937309980392456
2014	0.941649973392487
2015	0.941879987716675
2016	0.945460021495819
2017	0.94665002822876
2018	0.951659977436066
2019	0.955999970436096
2020	0.960049986839294