Year	Number
1971	33.04436
1972	35.3199
1973	42.16052
1974	43.1392
1975	41.049
1976	42.31662
1978	40.86184
1979	40.30923
1981	36.65918
1982	39.61955
1984	36.40654
1985	36.64584
1986	35.2156
1987	34.42947
1988	33.88861
1989	27.75215
1990	27.12057
1991	26.70661
1992	26.48119
1994	27.07671
1996	29.92472
2003	28.10852
2004	34.26944
2012	18.67603