Year	Percent
1967	33.39
1968	59.12
1969	51.41
1970	40.09
1971	15.46
1972	9.463
1973	23.65
1974	25.78
1975	24.45
1976	27.81
1977	26.8
1978	22.1
1979	21.24
1980	18.72
1981	24.64
1982	20
1983	18.6
1984	15.32
1985	18.45
1986	23.77
1987	18.11
1988	18.26
1989	12.28
1990	12.33
1991	16.19
1992	21.84
1993	15.33
1994	10.61
1995	10.81
1996	10.77
1997	13.03
1998	10.72
1999	9.528
2000	10.8
2001	12.93
2002	8.569
2003	6.668
2004	6.886
2005	5.343
2006	4.1
2007	13.09