Year	gross (GPI)
1971	0.918340027332306
1975	0.927240014076233
1976	0.923269987106323
1977	0.945590019226074
1983	0.960889995098114
1984	0.956770002841949
1986	0.961880028247833
1988	0.976270020008087
1989	0.975849986076355
1993	0.990580022335052
1994	0.990270018577576
1995	0.984860002994537
1996	0.9896399974823
1998	1.00685000419617
1999	1.01786005496979
2000	1.02583003044128
2001	1.02400994300842
2002	1.02295994758606
2003	1.02354001998901
2004	1.00171005725861
2005	0.995940029621124
2006	1.00691998004913
2007	1.02912998199463
2008	1.01893997192383
2009	1.01747000217438
2010	1.01159000396729
2011	1.00464999675751
2012	0.99769002199173
2013	1.01831996440887
2014	1.01443004608154
2015	1.00389003753662
2016	1.0010199546814
2017	0.995549976825714
2018	0.994610011577606
2019	0.987950026988983
2020	0.985019981861115