Year	gross (GPI)
1970	0.506699979305267
1971	0.506479978561401
1972	0.508930027484894
1973	0.511470019817352
1974	0.517260015010834
1975	0.518679976463318
1976	0.524160027503967
1977	0.504469990730286
1978	0.50067001581192
1979	0.499969989061356
1980	0.519919991493225
1981	0.512870013713837
1982	0.536870002746582
1983	0.553170025348663
1984	0.574930012226105
1985	0.577910006046295
1986	0.602180004119873
1987	0.605729997158051
1988	0.615109980106354
1989	0.624509990215302
1990	0.629220008850098
1991	0.643729984760284
1992	0.659049987792969
1993	0.670939981937408
1994	0.67738002538681
1995	0.712329983711243
1996	0.729770004749298
1997	0.748960018157959
1998	0.768369972705841
1999	0.784489989280701
2000	0.801159977912903
2001	0.805499970912933
2002	0.815299987792969
2003	0.818610012531281
2004	0.793479979038239
2005	0.809409976005554
2006	0.80952000617981
2007	0.818080008029938
2008	0.835730016231537
2009	0.837010025978088
2010	0.858969986438751
2011	0.876999974250793
2012	0.884999990463257
2013	0.886910021305084
2014	0.89546000957489
2015	0.913079977035522
2016	0.91609001159668
2017	0.932969987392426
2018	0.936999976634979
2019	0.937290012836456
2020	0.945890009403229