Year	gross (GPI)
1971	1.04570996761322
1972	0.991460025310516
1973	0.961880028247833
1974	0.948620021343231
1975	0.984350025653839
1976	1.07635998725891
1977	1.06518995761871
1978	1.06781995296478
1979	1.07093000411987
1980	1.05853998661041
1987	1.04706001281738
1988	1.04670000076294
1989	1.04431998729706
1990	1.04289996623993
1998	1.04410004615784
2008	0.970070004463196
2009	0.96917998790741
2010	0.967930018901825
2011	0.967249989509583
2012	0.964630007743835
2013	0.97503000497818
2014	0.980769991874695
2015	0.984759986400604
2016	0.983500003814697
2017	0.984709978103638
2018	0.985859990119934
2019	0.989629983901978
2020	0.985059976577759
2021	0.984879970550537