Year	gross (GPI)
1971	0.537679970264435
1972	0.544879972934723
1973	0.551389992237091
1974	0.555719971656799
1981	0.622829973697662
1983	0.635879993438721
1984	0.645749986171722
1999	0.69038999080658
2011	0.779177784919739
2013	0.794897019863129
2014	0.807550013065338
2015	0.818220019340515
2016	0.833500027656555
2017	0.850669980049133
2018	0.867879986763
2019	0.884140014648438
2020	0.898069977760315
2021	0.915130019187927