Year	Percent
1967	59.54
1968	67
1969	64.69
1970	69.86
1971	43.73
1972	27.82
1973	67.11
1974	48.98
1975	37.85
1976	49.91
1977	55.27
1978	52.08
1979	65.8
1980	53.56
1981	51.32
1982	71.74
1983	65.48
1984	44.12
1985	48.35
1986	59.09
1987	40.4
1988	45.07
1989	39.81
1990	35.33
1991	31.84
1992	20.54
1993	25.24
1994	32.72
1995	26.31
1996	27.45
1998	24.09
1999	13.49
2000	10.24
2001	9.88
2002	11.65
2003	18.39
2004	19.05
2005	16.13
2006	16.76
2007	15.57