Year	Percent
1967	44.6
1968	25.29
1969	52.38
1970	35.93
1971	36.57
1972	30.11
1973	11.05
1974	21.67
1975	22.14
1976	27.16
1977	27.05
1978	28.55
1979	47.59
1980	20.84
1981	18.58
1982	12.8
1983	16.93
1984	14
1985	10.94
1986	4.888
1987	14.15
1988	19.6
1989	25.15
1990	11.55
1991	12.25
1992	15.99
1993	21.87
1994	34.3
1995	24.21
1996	20.45
1997	18.31
1998	14.75
1999	11.53
2000	11.38
2001	6.822
2002	11.03
2003	7.324
2004	6.905
2005	5.503
2006	4.944
2007	6.677