Year	gross (GPI)
1971	0.941209971904755
1972	0.933770000934601
1973	0.941389977931976
1974	0.945339977741241
1989	0.970619976520538
1990	0.972190022468567
1991	0.992150008678436
1992	1.00436997413635
1993	0.997850000858307
1994	1.0254499912262
1995	1.02906000614166
1996	1.02132999897003
1997	1.0047299861908
1998	1.0188399553299
1999	1.02304995059967
2000	1.02418005466461
2001	1.02306997776031
2002	1.02462005615234
2003	1.02456998825073
2004	1.02053999900818
2005	1.01900994777679
2006	1.0111700296402
2007	1.00003004074097
2008	0.996410012245178
2009	0.997699975967407
2010	0.991370022296906
2011	0.987230002880096
2012	0.990010023117065
2013	0.98769998550415
2014	0.995710015296936
2015	1.00037002563477
2016	0.997600018978119
2017	1.0037100315094
2018	1.00248003005981
2019	1.00329005718231
2020	1.00501000881195