Year	Number
1973	6.00877
1974	5.50746
1975	5.1118
1976	5.68166
1981	8.02222
1984	6.27673
1985	6.29091
1988	7.8964
1989	7.7991
1990	6.89373
1991	7.90333
2000	7.93412
2001	7.65064
2002	7.54674