Year	Percent
1948	2
1949	2
1950	2
1951	2
1952	2
1953	2
1954	4
1955	7
1956	7
1957	7
1958	7
1959	6
1960	6
1961	7
1962	7
1963	7
1964	7
1965	7
1966	7
1967	7
1968	7
1969	7
1970	7
1971	7
1972	6
1973	6
1974	7
1975	7
1976	9
1977	10
1978	11
1979	13
1980	14
1981	13
1982	13
1983	8
1984	14
1985	20
1986	25
1987	19
1988	15
1989	15
1990	13
1991	8
1992	9
1993	6
1994	10
1995	10
1996	9
1997	10
1998	6
1999	5
2000	7
2001	5
2002	6
2003	5
2004	7
2005	7
2006	7