Year	gross (GPI)
1971	0.841499984264374
1972	0.84553998708725
1973	0.854309976100922
1974	0.854579985141754
1976	0.87457001209259
1977	0.884800016880035
1978	0.887619972229004
1979	0.895269989967346
1980	0.912689983844757
1981	0.913030028343201
1982	0.913500010967255
1983	0.915950000286102
1984	0.920740008354187
1985	0.928170025348663
1986	0.926169991493225
1987	0.93901002407074
1988	0.940509974956512
1989	0.974089980125427
1994	0.978209972381592
1995	0.960789978504181
1996	0.976639986038208
1997	0.968779981136322
1999	0.972239971160889
2019	1.01601541042328