Year	gross (GPI)
1971	0.411489993333817
1972	0.434410005807877
1973	0.47095999121666
1974	0.487540006637573
1975	0.514890015125275
1976	0.529389977455139
1977	0.545870006084442
1978	0.580900013446808
1979	0.614030003547668
1980	0.639050006866455
1981	0.656859993934631
1982	0.68190997838974
1984	0.714770019054413
1985	0.726300001144409
1986	0.742169976234436
1987	0.737659990787506
1988	0.744260013103485
1989	0.758840024471283
1990	0.774030029773712
1991	0.797720015048981
1992	0.817049980163574
1993	0.836489975452423
1994	0.86201000213623
1995	0.885200023651123
1996	0.901149988174438
1997	0.954659998416901
1999	1.01112997531891
2000	1.04744005203247
2001	1.06335997581482
2002	1.06369996070862
2003	1.08735001087189
2004	1.09079003334045
2005	1.09557998180389
2006	1.09433996677399
2007	1.08138000965118
2008	1.03848004341125
2009	1.01119005680084
2010	1.03617000579834
2011	1.03872001171112