Year	gross (GPI)
1971	0.975619971752167
1972	0.975870013237
1973	1.01487994194031
1974	1.03156995773315
1975	1.04154002666473
1976	1.03782999515533
1977	0.989759981632233
1978	1.02448999881744
1979	1.0113799571991
2004	0.981220006942749
2005	0.973540008068085
2007	1.0127500295639
2013	0.983257710933685
2014	0.970557034015656
2015	0.975172638893127
2016	0.962192595005035
2017	0.96794068813324
2018	0.963387906551361
2019	0.958769619464874
2020	0.995851039886475
2021	0.996382057666779