Year	gross (GPI)
1981	0.987720012664795
1986	1.005499958992
1989	1.06519997119904
1990	1.02623999118805
1992	1.018630027771
1993	1.01392996311188
1994	1.02330005168915
1995	1.01495003700256
1996	0.976230025291443
1997	0.958750009536743
1998	0.948419988155365
1999	0.991659998893738
2000	0.986630022525787
2001	0.980220019817352
2002	0.982089996337891
2003	0.989260017871857
2004	0.993300020694733
2005	0.984130024909973
2006	0.985069990158081
2007	0.988990008831024
2008	0.992259979248047
2009	0.997659981250763
2010	0.992169976234436
2011	0.991089999675751
2012	0.98743999004364
2013	0.988600015640259
2014	0.990540027618408
2015	0.992709994316101
2016	0.989870011806488
2017	0.992089986801147
2018	0.993480026721954
2019	0.987770020961761
2020	0.996349990367889
2021	0.995109975337982