Year	Percent
1948	3
1949	4
1950	4
1951	4
1952	4
1953	4
1954	4
1955	5
1956	5
1957	5
1958	4
1959	4
1960	5
1961	5
1962	2
1963	2
1964	5
1965	5
1966	6
1967	6
1968	6
1969	6
1970	6
1971	7
1972	6
1973	4
1974	6
1975	7
1976	8
1977	8
1978	8
1979	5
1980	7
1981	15
1982	14
1983	18
1984	21
1985	13
1986	10
1987	10
1988	15
1989	18
1990	18
1991	17
1992	14
1993	12
1994	13
1995	15
1996	17
1997	16
1998	19
1999	12
2000	12
2001	10
2002	14
2003	8
2004	8
2005	7
2006	9