Year	gross (GPI)
1976	0.683080017566681
1977	0.715179979801178
1978	0.752780020236969
1979	0.743570029735565
1980	0.719389975070953
1981	0.679610013961792
1982	0.665149986743927
1983	0.671490013599396
1984	0.679870009422302
1985	0.696460008621216
1986	0.694779992103577
1987	0.727090001106262
1988	0.733410000801086
1989	0.742990016937256
1990	0.736810028553009
1991	0.750880002975464
1992	0.773620009422302
1993	0.787810027599335
1994	0.830609977245331
1995	0.85291999578476
1996	0.87415999174118
1997	0.879559993743896
2001	0.934689998626709
2003	0.94293999671936
2006	0.990369975566864
2007	0.999440014362335
2008	1.0129200220108
2009	1.02603995800018
2010	0.996550023555756