Year	gross (GPI)
1971	1.01170003414154
1972	1.02152001857758
1973	1.02174997329712
1974	1.02172994613647
1975	1.02230000495911
1976	1.02323997020721
1977	1.02155995368958
1978	1.02164995670319
1979	1.02162003517151
1980	1.02216994762421
1981	1.02409994602203
1982	1.02406001091003
1983	1.02428996562958
1984	1.02348005771637
1985	1.0176500082016
1986	1.01870000362396
1987	1.01870000362396
1988	1.02035999298096
1989	1.02250003814697
1990	1.0249400138855
1991	1.01665997505188
1992	1.01699995994568
1993	1.02228999137878
1994	1.01653003692627
1995	1.01602005958557
1998	1.01692998409271
1999	1.01672005653381
2013	1.00806999206543
2014	1.00704002380371
2015	1.0058399438858
2016	1.00643002986908
2017	1.00528001785278
2018	1.00449001789093
2019	1.00423002243042