Year	gross (GPI)
1971	0.989650011062622
1972	0.988860011100769
1973	0.990880012512207
1974	0.997900009155273
1975	1.01437997817993
1976	1.00197994709015
1977	1.00837004184723
1978	1.0262199640274
1979	1.0377299785614
1980	1.0344899892807
1981	1.05388998985291
1982	1.06476998329163
1983	1.04595005512238
1984	1.06551003456116
1985	1.05915999412537
1986	1.05379998683929
1987	1.05193996429443
1988	1.05232000350952
1989	1.0557199716568
1990	1.04133999347687
1991	1.03286004066467
1992	1.01402997970581
1993	0.975709974765778
1994	0.972869992256165
1995	0.950309991836548
1996	0.948159992694855
1997	0.961459994316101
1998	1.00348997116089
1999	1.0229799747467
2000	1.02453994750977
2001	1.02242004871368
2002	1.02052998542786
2003	1.01967000961304
2004	1.02854001522064
2005	1.00952994823456
2006	0.996159970760345
2007	0.987200021743774
2008	0.978299975395203
2009	0.976930022239685
2010	0.983969986438751
2011	0.988269984722137
2012	0.985599994659424
2013	0.96968001127243
2014	0.966929972171783
2015	0.975130021572113
2016	0.974009990692139
2017	0.956719994544983
2018	0.955389976501465
2019	0.951489984989166
2020	0.951499998569489