Year	gross (GPI)
1971	0.996940016746521
1972	0.99821001291275
1973	0.997810006141663
1974	1.00284004211426
1975	1.00379002094269
1976	0.995859980583191
1977	1.00363004207611
1983	1.00152003765106
1984	1.0008499622345
1986	1.00009000301361
1987	0.99533998966217
1988	0.999499976634979
1989	1.00446999073029
1993	0.9966099858284
1994	0.999729990959167
1995	0.99821001291275
1996	1.0090399980545
1997	1.00764000415802
1998	0.993210017681122
1999	0.975510001182556
2000	0.977699995040894
2001	0.983449995517731
2002	0.984099984169006
2003	0.979200005531311
2004	0.976909995079041
2005	0.976029992103577
2006	0.991450011730194
2007	1.0064799785614
2008	1.00683999061584
2009	1.00459003448486
2010	1.00653994083405
2011	1.00345003604889
2012	1.0040899515152
2013	0.993340015411377
2014	0.990369975566864
2015	0.999040007591248
2016	0.999000012874603
2017	0.999949991703033
2018	0.997550010681152
2019	1.00429999828339
2020	1.00788998603821