Year	gross (GPI)
1971	0.426420003175735
1972	0.479999989271164
1973	0.526340007781982
1974	0.547810018062592
1975	0.588180005550385
1976	0.618130028247833
1977	0.638339996337891
1978	0.674759984016418
1979	0.698149979114532
1980	0.72188001871109
1981	0.737450003623962
1982	0.765659987926483
1983	0.799210011959076
1984	0.814610004425049
1985	0.835219979286194
1986	0.856079995632172
1987	0.862990021705627
1988	0.875789999961853
1989	0.873499989509583
1990	0.879620015621185
1991	0.865899980068207
1992	0.875100016593933
1993	0.889020025730133
1994	0.904470026493073
1995	0.934390008449554
1996	0.957239985466003
1997	0.974229991436005
1998	0.998619973659515
2013	1.16927003860474
2014	1.16376996040344
2015	1.16585004329681
2016	1.17218995094299
2017	1.17297005653381
2018	1.17596995830536
2019	1.18473994731903
2020	1.19034004211426
2021	1.20816004276276