Year	gross (GPI)
1970	0.956229984760284
1971	0.959429979324341
1972	0.955290019512177
1973	0.960919976234436
1974	0.968789994716644
1975	0.978510022163391
1976	0.979900002479553
1977	0.978280007839203
1978	0.979510009288788
1979	0.99506002664566
1980	0.997510015964508
1981	1.00004005432129
1982	0.998179972171783
1983	0.997290015220642
1984	0.996309995651245
1985	0.985549986362457
1986	1.00093996524811
1987	1.00334000587463
1988	1.0082700252533
1989	1.0100200176239
1990	1.01510000228882
1991	1.01454997062683
1992	1.01324999332428
1993	1.0111700296402
1994	1.00864005088806
1995	1.00731003284454
1996	1.00320994853973
1997	1.00529003143311
1998	1.00462996959686
1999	1.0073299407959
2000	1.00942003726959
2001	1.00744998455048
2002	1.00715005397797
2003	1.01705002784729
2004	1.01644003391266
2005	1.01568996906281
2006	1.01756000518799
2007	1.02690994739532
2008	1.02742004394531
2009	1.02895998954773
2010	1.02171003818512
2011	1.02040994167328
2012	1.01841998100281
2013	1.01548004150391
2014	1.01596999168396
2015	1.01647996902466
2016	1.01425004005432
2017	1.01254999637604
2018	1.01467001438141
2019	1.01716005802155
2020	1.0171799659729