Year	Percent
1967	25.11
1968	20.32
1969	36.69
1970	20.41
1971	3.231
1972	1.405
1973	8.853
1974	4.495
1975	9.704
1976	10.64
1977	5.199
1978	9.344
1979	12.25
1980	12.95
1981	3.943
1982	5.35
1983	17.18
1984	16.07
1985	17.1
1986	18.23
1987	17.39
1988	19.42
1989	8.147
1990	12.91
1991	10.63
1992	9.843
1993	9.674
1994	11.91
1995	11.44
1996	6.453
1997	5.918
1998	6.277
1999	4.779
2000	7.308
2001	11.46
2002	10.3
2003	12.6
2004	14.12
2005	13.12
2006	10.94
2007	10.03