Year	gross (GPI)
1970	0.989040017127991
1986	0.992160022258759
1987	0.991400003433228
1988	0.991270005702972
1989	1.00327003002167
1990	1.00240004062653
1991	1.00082004070282
1994	0.977739989757538
1995	0.991509974002838
1997	0.982400000095367
1998	0.982609987258911
1999	0.979179978370667
2000	0.958949983119965
2001	0.97136002779007
2002	0.973479986190796
2003	0.970459997653961
2004	0.966229975223541
2005	0.966229975223541
2006	0.964990019798279
2007	0.969640016555786
2008	0.969330012798309
2009	0.965659976005554
2010	0.961709976196289
2011	0.959550023078918
2012	0.9582399725914
2013	0.957830011844635
2014	0.961239993572235
2015	0.933380007743835
2016	0.968039989471436
2017	0.966669976711273
2018	0.961589992046356
2019	0.965240001678467
2020	0.959590017795563