Year	gross (GPI)
1970	0.941720008850098
1971	0.941850006580353
1972	0.944790005683899
1973	0.953559994697571
1974	0.94811999797821
1975	0.968670010566711
1976	0.972620010375977
1977	0.978789985179901
1978	0.985989987850189
1979	0.987689971923828
1980	0.99576997756958
1981	1.01174998283386
1982	1.00019001960754
1983	1.01183998584747
1984	1.00989997386932
1985	1.01285004615784
1986	1.01692998409271
1987	1.01628005504608
1988	1.01414000988007
1989	1.01324999332428
1990	1.01240003108978
1991	1.01411998271942
1992	1.01664996147156
1993	1.01515996456146
1994	1.00522005558014
1995	1.0066100358963
1996	1.01021003723145
1997	1.00551998615265
1998	1.00425004959106
1999	1.00587999820709
2000	1.00294995307922
2001	1.00548005104065
2002	1.00311005115509
2003	1.00363004207611
2004	1.00506997108459
2005	1.00425004959106
2006	1.0022200345993
2007	1.00356996059418
2008	1.00352001190186
2009	0.995739996433258
2010	0.993799984455109
2011	0.991310000419617
2012	0.989769995212555
2013	0.994180023670197
2014	0.995050013065338
2015	0.99440997838974
2016	0.994920015335083
2017	0.991370022296906
2018	0.99456000328064
2019	0.995809972286224
2020	0.998350024223328