Year	gross (GPI)
1971	0.93997997045517
1972	0.910179972648621
1974	0.941720008850098
1975	0.926440000534058
1976	0.927820026874542
1977	0.958599984645844
1978	0.947380006313324
1979	0.974129974842072
1980	0.987129986286163
1981	0.977119982242584
1982	0.971819996833801
1983	0.951910018920898
1984	0.951839983463287
1985	0.963039994239807
1986	0.968150019645691
1987	0.97188001871109
1988	0.973110020160675
1989	0.974810004234314
1990	0.966910004615784
1991	0.971449971199036
1992	0.967960000038147
1993	0.966970026493073
1994	0.962610006332397
1995	0.966899991035461
1996	0.96697998046875
1997	0.966310024261475
1998	0.967880010604858
1999	0.970979988574982
2000	0.975329995155334
2001	0.97936999797821
2002	0.981790006160736
2003	0.983139991760254
2004	0.984279990196228
2005	0.98198002576828
2006	0.980080008506775
2007	0.979709982872009
2008	0.980300009250641
2009	0.982599973678589
2010	0.985939979553223
2011	0.988479971885681
2012	0.991169989109039
2013	0.992240011692047
2014	0.994470000267029
2015	0.997529983520508
2016	1.0010199546814
2017	1.00490999221802
2018	1.00621998310089
2019	1.00910997390747
2020	1.00940001010895