Year	gross (GPI)
1971	1.03411996364594
1972	1.03698003292084
1973	1.01347994804382
1974	1.00510001182556
1975	1.00799000263214
1976	1.00626003742218
1977	1.00211000442505
1978	0.996569991111755
1979	0.99848997592926
1980	1.00325000286102
1981	1.00180995464325
1982	0.993669986724854
1983	0.990930020809174
1984	0.987929999828339
1985	0.988919973373413
1986	0.988900005817413
1987	1.00065994262695
1988	0.985769987106323
1989	0.985610008239746
1990	0.983959972858429
1991	0.992370009422302
1992	0.986039996147156
1993	0.981809973716736
1994	0.981169998645782
1995	0.984610021114349
1996	0.981859982013702
1997	0.988730013370514
1998	0.990140020847321
1999	0.990700006484985
2000	0.993009984493256
2001	0.992500007152557
2002	0.991209983825684
2003	0.989589989185333
2004	0.990010023117065
2005	0.986720025539398
2006	0.985809981822968
2007	0.988749980926514
2008	0.990660011768341
2009	0.991580009460449
2010	0.992529988288879
2011	0.992410004138947
2012	0.993749976158142
2013	1.01124000549316
2014	1.01323997974396
2015	1.01551997661591
2016	1.01656997203827
2017	1.01662003993988
2018	1.01365995407104
2019	1.01298999786377
2020	1.01031005382538