Year	gross (GPI)
1971	0.777220010757446
1972	0.792289972305298
1973	0.818989992141724
1974	0.850809991359711
1975	0.875220000743866
1976	0.917670011520386
1977	0.92058002948761
1978	0.951789975166321
1979	0.998740017414093
1980	1.02388000488281
1981	1.04752004146576
1982	1.06933999061584
1983	1.0900399684906
1984	1.08972001075745
1985	1.07842004299164
1986	1.08201003074646
1987	1.06814002990723
1988	1.04551994800568
1996	1.0493700504303
2001	1.00880002975464
2002	0.999960005283356
2003	1.00460004806519
2004	1.00652003288269
2005	1.00958001613617
2006	1.00756001472473
2007	1.00461995601654
2008	1.00397002696991
2009	1.00598001480103
2010	1.00318002700806
2011	1.00396001338959
2012	1.00511002540588
2013	0.987929999828339
2014	0.983210027217865
2015	0.983659982681274
2016	0.979399979114532
2017	0.969569981098175
2018	0.969929993152618
2019	0.977010011672974
2020	0.986289978027344
2021	0.994069993495941