Year	gross (GPI)
1970	0.375589996576309
1974	0.454189985990524
1975	0.413839995861053
1976	0.410569995641708
1977	0.411300003528595
1984	0.570429980754852
1986	0.5798100233078
1987	0.553990006446838
1988	0.565670013427734
1989	0.592440009117126
1990	0.644980013370514
1991	0.661109983921051
1992	0.659839987754822
1993	0.676900029182434
1994	0.68462997674942
1995	0.67833000421524
1998	0.704850018024445
2012	0.750739991664886
2018	0.799239993095398