Year	gross (GPI)
1971	0.736909985542297
1972	0.804989993572235
1973	0.877520024776459
1974	0.929120004177094
1975	0.76842999458313
1976	0.816779971122742
1977	0.765770018100739
1978	0.74796998500824
1979	0.907069981098175
1980	0.920960009098053
1981	0.948409974575043
1982	0.999170005321503
1983	1.01727998256683
1984	1.18166995048523
1985	1.11854004859924
1986	1.14611005783081
1987	1.0702999830246
1991	1.22475004196167
1992	1.36286997795105
1993	1.23405003547668
1994	1.25670003890991
1995	1.25086998939514
1996	1.24800002574921
1998	1.23528003692627
1999	1.23071002960205
2015	1.15038001537323
2016	1.14347994327545
2017	1.15376996994019
2018	1.16036999225616
2019	1.16666996479034
2020	1.16696000099182
2021	1.16229999065399