Year	gross (GPI)
1971	0.995369970798492
1972	0.995930016040802
1973	0.999199986457825
1974	1.00468003749847
1975	1.007159948349
1976	0.981750011444092
1977	1.00829994678497
1978	0.976469993591309
1979	0.978219985961914
1980	0.969070017337799
1981	0.962689995765686
1982	0.983179986476898
1983	0.962790012359619
1984	0.989329993724823
1985	0.946699976921082
1986	0.957490026950836
1987	0.962189972400665
1988	0.969370007514954
1989	0.988370001316071
1990	0.974730014801025
1991	0.971080005168915
1992	0.97367000579834
1993	0.979749977588654
1994	0.980400025844574
1995	0.967369973659515
1996	0.993659973144531
1997	0.995949983596802
1998	1.00922000408173
1999	1.00871002674103
2000	1.00875997543335
2001	0.998690009117126
2002	0.990069985389709
2003	0.984480023384094
2004	0.987129986286163
2005	0.975340008735657
2006	0.998870015144348
2007	0.995639979839325
2008	0.996060013771057
2009	1.0013200044632
2010	1.00293004512787
2011	1.01172995567322
2012	1.00100994110107
2013	1.00508999824524
2014	1.01408994197845
2015	1.01476001739502
2016	1.02111005783081
2017	1.00192999839783
2018	1.00677001476288
2019	1.00782001018524
2020	0.996710002422333