Year	gross (GPI)
1971	0.919669985771179
1972	0.933520019054413
1973	0.955889999866486
1974	0.949000000953674
1975	0.958119988441467
1976	0.963429987430573
1977	0.97036999464035
1978	0.973119974136353
1979	0.978890001773834
1980	0.980579972267151
1981	0.986039996147156
1982	0.997349977493286
1983	0.997479975223541
1984	0.997460007667542
1985	0.999719977378845
1986	1.00223994255066
1987	1.00522005558014
1988	1.0074599981308
1989	1.00946998596191
1990	1.00337994098663
1991	1.00206995010376
1992	1.00167000293732
1994	1.01837003231049
1995	1.01998996734619
1996	1.01839005947113
1997	1.01517999172211
1998	1.00914001464844
1999	1.00332999229431
2000	0.998870015144348
2001	0.998799979686737
2002	0.998769998550415
2003	0.995679974555969
2004	0.988340020179749
2005	0.986620008945465
2006	0.987890005111694
2007	0.990750014781952
2008	0.9860600233078
2009	0.990019977092743
2010	0.988900005817413
2011	0.985989987850189
2012	0.986209988594055
2013	1.00150001049042
2014	1.00186002254486
2015	1.00296998023987
2016	0.993550002574921
2017	0.99905002117157
2018	0.994589984416962
2019	0.993380010128021
2020	0.989939987659454