Year	gross (GPI)
1970	0.720399975776672
1971	0.720560014247894
1972	0.724749982357025
1973	0.729070007801056
1974	0.733020007610321
1975	0.73361998796463
1976	0.73387998342514
1977	0.743789970874786
1978	0.750270009040833
1979	0.753750026226044
1980	0.759570002555847
1981	0.7673100233078
1982	0.782909989356995
1983	0.773069977760315
1984	0.76596999168396
1985	0.780170023441315
1986	0.799000024795532
1987	0.812879979610443
1988	0.799650013446808
1989	0.817080020904541
1990	0.807929992675781
1991	0.816349983215332
1992	0.824829995632172
1993	0.820230007171631
1994	0.814090013504028
1995	0.81360000371933
1996	0.812940001487732
1997	0.806850016117096
1998	0.800899982452393
1999	0.806240022182465
2000	0.806550025939941
2001	0.807399988174438
2002	0.804289996623993
2003	0.81155002117157
2004	0.805450022220612
2005	0.823589980602264
2006	0.832539975643158
2007	0.839110016822815
2008	0.849560022354126
2009	0.85971999168396
2010	0.867299973964691
2011	0.874689996242523
2012	0.889119982719421
2013	0.893180012702942
2014	0.893469989299774
2015	0.901950001716614
2016	0.897580027580261
2017	0.901229977607727
2018	0.904120028018951
2019	0.902559995651245