Year	gross (GPI)
1970	0.899070024490356
1971	0.891520023345947
1972	0.886039972305298
1973	0.895120024681091
1974	0.904910027980804
1975	0.908410012722015
1976	0.918900012969971
1977	0.924369990825653
1978	0.928879976272583
1979	0.931460022926331
1980	0.945230007171631
1981	0.938510000705719
1982	0.933059990406036
1983	0.932110011577606
1984	0.927590012550354
1985	0.937290012836456
1986	0.939970016479492
1987	0.948069989681244
1988	0.956380009651184
1989	0.966970026493073
1990	0.978269994258881
1991	0.984520018100739
1992	0.990840017795563
1993	0.989260017871857
1994	0.997150003910065
1995	0.988189995288849
1996	0.994759976863861
1997	0.989970028400421
1998	0.98988002538681
1999	0.977389991283417
2000	0.977050006389618
2001	0.975820004940033
2002	0.978910028934479
2003	0.977519989013672
2004	0.967310011386871
2005	0.970669984817505
2006	0.986090004444122
2007	0.995169997215271
2008	1.00634002685547
2009	1.00957000255585
2010	1.00697004795074
2011	1.00475001335144
2012	1.02339005470276
2013	1.03000998497009
2014	1.03190994262695
2015	1.02953004837036
2016	1.03058004379272
2017	1.04217004776001
2018	1.04448997974396
2019	1.04199004173279
2020	1.03971004486084