Year	gross (GPI)
1970	0.649410009384155
1971	0.661090016365051
1972	0.638469994068146
1973	0.666220009326935
1974	0.681659996509552
1975	0.710879981517792
1976	0.721949994564056
1977	0.743520021438599
1978	0.765380024909973
1979	0.830169975757599
1981	0.728649973869324
1982	0.704029977321625
1983	0.692759990692139
1984	0.683969974517822
1985	0.685140013694763
1986	0.681620001792908
1987	0.713379979133606
1988	0.724799990653992
1989	0.739610016345978
1990	0.88289999961853
1991	0.791270017623901
1992	0.790859997272491
1993	0.802990019321442
1994	0.822390019893646
1995	0.842190027236938
1996	0.859080016613007
1999	0.882189989089966
2000	0.876800000667572
2001	0.875169992446899
2002	0.864279985427856
2003	0.878740012645721
2012	0.946550011634827
2013	0.959890007972717