Year	Number
1976	17.94776
1983	17.95956
1984	17.79462
1985	15.15465
1986	14.86849
1987	14.62825
1988	14.33856
1989	14.35412
1990	14.21436
1991	13.96799
1992	14.04705
1993	17.82306
1994	18.06949
1995	18.51821
1996	18.79864