Year	gross (GPI)
1971	0.294900000095367
1972	0.298269987106323
1973	0.319750010967255
1974	0.365110009908676
1976	0.506990015506744
1977	0.532379984855652
1978	0.558879971504211
1979	0.552349984645844
1980	0.56165999174118
1981	0.540750026702881
1982	0.536729991436005
1983	0.532159984111786
1984	0.548870027065277
1985	0.53355997800827
1986	0.5173100233078
2007	0.53710001707077