Year	gross (GPI)
1971	0.965380012989044
1972	0.998769998550415
1973	0.960139989852905
1977	0.971109986305237
1978	0.969780027866364
1979	0.989769995212555
1980	0.977959990501404
1981	0.99414998292923
1982	1.00078999996185
1983	1.00303995609283
1984	1.00673997402191
1985	1.00436997413635
1986	1.01367998123169
1987	1.00278997421265
1988	1.00973999500275
1989	1.04303002357483
1990	1.01630997657776
1991	0.997780025005341
1992	1.00013995170593
1993	1.01108002662659
1994	1.01389002799988
1995	1.02509999275208
1996	1.0349600315094
1997	1.02651000022888
1998	1.03217995166779
1999	1.02875995635986
2000	0.991490006446838
2001	1.04815995693207
2002	1.02523005008698
2003	0.999289989471436
2004	1.03621995449066
2005	1.01445996761322
2006	0.989030003547668
2007	1.02643001079559
2008	1.04723000526428
2009	1.05536997318268
2010	1.07902598381042
2011	1.05937933921814
2012	1.03577697277069
2013	1.04152655601501
2014	1.01566994190216
2015	1.02040994167328
2016	1.02321994304657
2017	1.07131004333496
2020	1.0568300485611