Year	Number
1971	15.21527
1972	13.36744
1973	12.10769
1974	13.47931
1975	13.5836
1976	14.61781
1977	14.19262
1979	11.28992
1980	11.73197
1982	12.8147
1983	12.61389
1984	11.97992
1992	14.2546
1993	14.75859
1994	14.97417