Year	gross (GPI)
1971	0.421480000019073
1973	0.49439001083374
1974	0.526700019836426
1975	0.544120013713837
1976	0.518830001354218
1982	0.714699983596802
1983	0.722230017185211
1984	0.71833997964859
1985	0.710219979286194
1986	0.705200016498566
1987	0.714609980583191
1988	0.723209977149963
1989	0.724940001964569
1992	0.714789986610413
1993	0.776970028877258
1994	0.766889989376068
1995	0.755720019340515
1996	0.747039973735809
1997	0.738460004329681
1999	0.719129979610443
2000	0.715020000934601
2001	0.711279988288879
2002	0.717509984970093
2004	0.750240027904511
2005	0.75586998462677
2006	0.764829993247986
2007	0.820469975471497
2008	0.854839980602264
2009	0.906270027160645
2011	1.00932002067566
2012	0.992999970912933
2013	0.983290016651154
2014	1.00177001953125
2015	1.00581002235413
2016	1.01397001743317
2017	1.02550005912781
2018	1.0144499540329
2019	1.02002000808716
2020	1.00286996364594
2021	0.972949981689453