Year	gross (GPI)
1970	0.808480024337769
1971	0.815379977226257
1972	0.81207001209259
1973	0.816969990730286
1974	0.826579988002777
1975	0.838689982891083
1976	0.847090005874634
1977	0.862999975681305
1978	0.868579983711243
1979	0.871749997138977
1981	0.910809993743896
1982	0.904709994792938
1983	0.899879992008209
1984	0.896120011806488
1985	0.896449983119965
1986	0.901419997215271
1987	0.912930011749268
1988	0.91755998134613
1989	0.927990019321442
1990	0.970749974250793
1991	0.927990019321442
1992	0.945150017738342
1995	0.947090029716492
1996	0.949280023574829
1999	0.949090003967285
2000	0.945620000362396
2001	0.943849980831146
2002	0.942330002784729
2003	0.9478600025177
2012	0.967029988765717
2013	0.970120012760162