Year	gross (GPI)
1970	0.97597998380661
1971	0.976199984550476
1972	0.97775000333786
1973	0.985430002212524
1974	0.978280007839203
1975	0.986660003662109
1976	0.993149995803833
1977	0.990800023078918
1978	0.993759989738464
1979	0.993900001049042
1980	0.998359978199005
1981	1.00554001331329
1982	1.00169003009796
1983	1.00612998008728
1984	1.00467002391815
1985	1.00530004501343
1986	1.00706005096436
1987	1.00839996337891
1988	1.0064799785614
1989	1.00410997867584
1990	1.00419998168945
1991	1.00752997398376
1992	1.01034998893738
1993	1.00637996196747
1994	1.00206005573273
1995	1.00236999988556
1996	1.00355994701385
1997	1.00163996219635
1998	1.00216996669769
1999	1.00293004512787
2000	1.00192999839783
2001	1.00285005569458
2002	1.00090003013611
2003	1.0019199848175
2004	1.00248003005981
2005	1.00059998035431
2006	0.999450027942657
2007	0.999270021915436
2008	0.998390018939972
2009	0.995530009269714
2010	0.993900001049042
2011	0.993480026721954
2012	0.993110001087189
2013	1.00093996524811
2014	1.0013200044632
2015	1.0008100271225
2016	1.00092995166779
2017	0.997879981994629
2018	0.99848997592926
2019	0.999880015850067
2020	1.00203001499176