Year	gross (GPI)
1971	0.872349977493286
1973	0.880370020866394
1974	0.881359994411469
1975	0.889079988002777
1976	0.897449970245361
1977	0.90693998336792
1978	0.915189981460571
1991	0.972239971160889
1992	0.974089980125427
1993	0.974720001220703
2001	0.976549983024597
2002	0.985090017318726
2004	1.01288998126984
2005	1.00288999080658
2006	1.01591002941132
2007	1.02389001846313
2008	1.02392995357513
2009	1.02934002876282
2010	1.02680003643036
2011	1.02875995635986
2012	1.0271600484848
2013	1.03692996501923
2014	1.03778004646301
2015	0.953830003738403
2016	0.999880015850067
2017	0.993813335895538
2018	1.02044188976288
2019	0.995571434497833
2020	0.995733320713043
2021	1.01338183879852
2022	1.02751123905182