Year	gross (GPI)
1970	0.996829986572266
1971	0.997489988803864
1972	0.999459981918335
1973	1.00266003608704
1974	1.00093996524811
1975	1.00370001792908
1976	1.00273001194
1977	1.00480997562408
1978	1.00373995304108
1979	1.0040500164032
1980	1.00415003299713
1981	1.0066100358963
1982	1.00943994522095
1983	1.00957000255585
1984	1.01010000705719
1985	1.0112099647522
1986	1.01267004013062
1987	1.02565002441406
1988	1.02634000778198
1989	1.00257003307343
1990	0.998979985713959
1991	1.01003003120422
1992	1.02198994159698
1993	1.01450002193451
1994	1.01767003536224
1995	1.02428996562958
1996	1.02013003826141
1997	1.01401996612549
1998	1.01478004455566
1999	1.01108002662659
2000	1.00443994998932
2001	1.0019199848175
2002	0.997940003871918
2003	0.992649972438812
2004	1.00822997093201
2005	1.00173997879028
2006	0.99822998046875
2007	0.99752002954483
2008	0.998369991779327
2009	0.999279975891113
2010	0.995620012283325
2011	0.990890026092529
2012	0.990379989147186
2013	0.984070003032684
2014	0.985599994659424
2015	0.988460004329681
2016	0.98812997341156
2017	0.991479992866516
2018	0.991590023040771
2019	0.994069993495941
2020	0.998099982738495