Year	gross (GPI)
1971	0.642530024051666
1972	0.644959986209869
1973	0.653339982032776
1974	0.654089987277985
1975	0.656140029430389
1976	0.661220014095306
1977	0.663420021533966
1978	0.652159988880157
1979	0.664860010147095
1980	0.668590009212494
1981	0.67562997341156
1982	0.67562997341156
1983	0.6841099858284
1984	0.688080012798309
1985	0.70441997051239
1986	0.727020025253296
1987	0.741540014743805
1988	0.748319983482361
1989	0.733940005302429
1990	0.747460007667542
1991	0.772369980812073
1992	0.78439998626709
1993	0.816240012645721
1994	0.825789988040924
1995	0.827579975128174
1996	0.837740004062653
1997	0.846099972724915
1998	0.851300001144409
1999	0.853479981422424
2000	0.858829975128174
2001	0.868399977684021
2002	0.885450005531311
2003	0.986150026321411
2007	0.992999970912933
2008	1.0199099779129
2009	1.0322300195694
2010	1.02796995639801
2011	1.03262948989868
2012	1.03737425804138
2013	1.04935085773468
2014	1.04157137870789
2015	1.03849303722382
2016	1.03597581386566
2017	1.02605366706848
2018	1.02145993709564
2019	1.0192049741745
2020	1.01903808116913
2021	1.01563942432404