Year	Number
1975	12.06206
1977	10.97824
1978	10.8898
1979	10.56527
1980	10.58564
1981	10.56638
1982	11.11796
1983	11.08189
1984	10.89591
1985	10.53147
1986	10.95521
1987	11.05142
1988	10.90245
1989	10.92047
1990	10.8389
1991	10.51905
1992	10.41338
1993	10.18273
1994	9.76723
1999	10.40233
2000	10.6371
2001	9.97081
2002	9.8969
2003	9.83352
2004	9.78642
2005	9.88565
2006	10.07465
2007	10.05727
2008	9.89721
2009	9.76439