Year	Percent
1948	3
1949	3
1950	3
1951	3
1952	3
1953	3
1954	3
1955	4
1956	4
1957	5
1958	5
1959	5
1960	5
1961	5
1962	4
1963	4
1964	5
1965	6
1966	6
1967	6
1968	5
1969	7
1970	7
1971	5
1972	5
1973	5
1974	7
1975	6
1976	8
1977	8
1978	7
1979	9
1980	10
1981	11
1982	10
1983	9
1984	10
1985	11
1986	8
1987	8
1988	9
1989	11
1990	12
1991	8
1992	10
1993	5
1994	7
1995	7
1996	4
1997	3
1998	2
1999	2
2000	2
2001	2
2002	5
2003	3
2004	2
2005	2
2006	3