Year	gross (GPI)
1971	0.287499994039536
1972	0.277440011501312
1973	0.265670001506805
1974	0.337760001420975
1975	0.417879998683929
1976	0.494309991598129
1977	0.476669996976852
1978	0.48827001452446
1979	0.486090004444122
1980	0.453810006380081
1981	0.473659992218018
1982	0.454780012369156
1983	0.468679994344711
1984	0.4792700111866
1985	0.412880003452301
1986	0.573450028896332
1987	0.639530003070831
1988	0.657169997692108
1989	0.613759994506836
1999	0.537169992923737
2000	0.533810019493103
2002	0.533840000629425
2004	0.585520029067993
2005	0.584519982337952