Year	gross (GPI)
1971	1.10127997398376
1972	0.998910009860992
1973	1.00279998779297
1974	1.00153005123138
1975	1.00317001342773
1976	1.00292003154755
1977	1.00044000148773
1978	1.00181996822357
1979	1.00255000591278
1980	1.00437998771667
1981	1.00093996524811
1982	1.00177001953125
1983	1.00141000747681
1984	1.0025999546051
1985	1.0005099773407
1986	1.00002002716064
1987	1.00398004055023
1988	0.998099982738495
1989	0.999140024185181
1990	1.00116002559662
1991	0.999029994010925
1992	1.00062000751495
1993	1.0035799741745
1994	1.00152003765106
1995	0.998730003833771
1996	1.00041997432709
1997	1.00241994857788
1998	1.00220000743866
1999	0.99822998046875
2000	1.00257003307343
2001	1.00172996520996
2002	1.00253999233246
2003	1.00068998336792
2004	1.00170004367828
2005	1.00296998023987
2006	1.00662994384766
2007	1.00147998332977
2008	1.00262999534607
2009	1.00319004058838
2010	1.0030699968338
2011	1.0020500421524
2012	1.0042200088501
2013	0.999040007591248
2014	0.999270021915436
2015	0.99728000164032
2016	0.997749984264374
2017	0.999180018901825
2018	0.999989986419678
2019	0.999819993972778
2020	1.00313997268677