Year	gross (GPI)
1971	1.02604997158051
1972	1.0211900472641
1973	1.0314199924469
1974	1.03215003013611
1975	1.03944003582001
1976	1.03720998764038
1977	1.03949999809265
1978	1.04499995708466
1979	1.04697000980377
1980	1.05396997928619
1981	1.05225002765656
1982	1.05185997486115
1983	1.04754996299744
1984	1.04539000988007
1985	1.04512000083923
1986	1.04744005203247
1987	1.04571998119354
1988	1.04355001449585
1989	1.04498994350433
1990	1.0483900308609
1991	1.04619002342224
1992	1.04193997383118
1993	1.01974999904633
1994	1.02333998680115
1995	1.02963995933533
1996	1.03813004493713
1997	1.04237997531891
1998	1.02313005924225
1999	1.02216994762421
2000	1.02795994281769
2001	1.03173995018005
2002	1.0358099937439
2003	1.03082001209259
2004	1.02734005451202
2005	1.03352999687195
2006	1.02732002735138
2007	1.02099001407623
2008	1.02286994457245
2009	1.02594995498657
2010	1.02363002300262
2011	1.01397001743317
2012	1.0105299949646
2014	1.00741004943848
2015	1.00846004486084
2016	1.00690996646881
2017	0.991919994354248
2018	1.0602400302887
2019	1.04007995128632
2020	1.04173004627228