Year	gross (GPI)
1971	0.983120024204254
1972	0.980449974536896
1973	0.988160014152527
1974	0.989629983901978
1975	0.997730016708374
1976	0.993740022182465
1977	1.00440001487732
1978	0.991500020027161
1979	0.99466997385025
1980	1.00692999362946
1981	0.871659994125366
1982	0.972230017185211
1983	0.954200029373169
1984	0.953890025615692
1986	0.992160022258759
1987	0.998920023441315
1988	1.01935005187988
1999	1.02869999408722
2000	1.03480994701385
2001	1.03093004226685
2002	1.02813005447388
2003	1.02567994594574
2004	1.02372002601624
2005	1.02759003639221
2006	1.02146005630493
2007	1.01653003692627
2008	1.01803994178772
2010	1.02114999294281
2011	1.02648997306824
2012	1.02052998542786
2013	1.01679003238678
2014	1.01379001140594
2015	1.02044999599457
2016	1.01610004901886
2017	1.00945997238159
2018	1.00028002262115
2019	0.992669999599457
2020	0.992569983005524