Year	gross (GPI)
1971	0.59909999370575
1972	0.62364000082016
1973	0.640470027923584
1974	0.647710025310516
1975	0.658050000667572
1976	0.667249977588654
1977	0.680890023708344
1978	0.691020011901855
1979	0.707639992237091
1980	0.719709992408752
1981	0.729340016841888
1982	0.738340020179749
1984	0.756640017032623
1985	0.767359972000122
1986	0.782750010490417
1987	0.789659976959229
1988	0.797330021858215
1989	0.808520019054413
1990	0.817080020904541
1991	0.829490005970001
1992	0.84263002872467
1993	0.854430019855499
1994	0.870299994945526
1995	0.883539974689484
1996	0.895179986953735
1997	0.918340027332306
1999	0.948920011520386
2000	0.964209973812103
2001	0.974020004272461
2002	0.980109989643097
2003	0.990549981594086
2004	0.995850026607513
2005	0.999260008335114
2006	1.00127995014191
2007	1.00127995014191
2008	0.986199975013733
2009	0.979049980640411
2010	0.993629992008209
2011	0.994899988174438