Year	gross (GPI)
1970	0.588890016078949
1971	0.593959987163544
1972	0.606639981269836
1973	0.623529970645905
1974	0.625169992446899
1975	0.627409994602203
1976	0.625490009784698
1977	0.629140019416809
1978	0.63756000995636
1979	0.656130015850067
1980	0.634930014610291
1981	0.639270007610321
1982	0.642419993877411
1983	0.582690000534058
1984	0.550740003585815
1985	0.61505001783371
1986	0.691410005092621
1987	0.710380017757416
1988	0.71272999048233
1989	0.710979998111725
1990	0.710730016231537
1991	0.722199976444244
1992	0.725130021572113
1993	0.736440002918243
1994	0.749109983444214
1995	0.763130009174347
1996	0.777530014514923
1997	0.792940020561218
1998	0.803269982337952
1999	0.82107001543045
2000	0.812740027904511
2001	0.818970024585724
2002	0.800819993019104
2003	0.829339981079102
2004	0.829069972038269
2005	0.849449992179871
2006	0.84705001115799
2007	0.823050022125244
2008	0.844839990139008
2009	0.868910014629364
2010	0.86259001493454
2011	0.848299980163574
2012	0.860300004482269
2013	0.861100018024445
2014	0.872300028800964
2015	0.878419995307922
2016	0.879599988460541
2017	0.88798999786377
2018	0.909330010414124
2019	0.914939999580383
2020	0.914830029010773