Year	Percent
1967	100
1968	47.88
1969	24.16
1970	40.06
1971	6.321
1972	4.199
1973	32.26
1974	35.47
1975	39.69
1976	30.93
1977	38.33
1978	44.39
1979	43.39
1980	31.69
1981	40.15
1982	33.84
1983	35.92
1984	31.26
1985	28.36
1986	34.79
1987	41.47
1988	33.69
1989	34.75
1990	33.37
1991	33.56
1992	27.43
1993	30.57
1994	32.1
1995	21.08
1996	15.22
1997	14.78
1998	18.19
1999	13.12
2000	7.986
2001	11.9
2002	7.484
2003	7.484
2004	7.794
2005	7.246
2006	4.439
2007	5.91