Year	gross (GPI)
1973	0.0510499998927116
1974	0.044259998947382
1975	0.123620003461838
1976	0.119690001010895
1977	0.173950001597404
1978	0.187089994549751
1979	0.210960000753403
1980	0.210400000214577
1981	0.256619989871979
1982	0.2204499989748
1983	0.197669997811317
1984	0.283840000629425
1985	0.233869999647141
1987	0.224910005927086
1989	0.202370002865791
1990	0.18299999833107
2003	0.392800003290176
2004	0.39708000421524
2005	0.440400004386902
2006	0.380459994077682
2007	0.417879998683929
2008	0.438969999551773
2009	0.42645001411438
2010	0.442530006170273
2011	0.455549985170364
2012	0.402579993009567
2015	0.479600012302399
2016	0.56045001745224
2017	0.49210000038147
2018	0.414380013942719
2019	0.636170029640198
2020	0.48072561621666