Year	Percent
1971	47.15
1972	14.79
1973	9.273
1975	2.083
1976	1.52
1977	15.58
1978	4.262
1979	3.768
1980	9.744
1981	10.57
1982	1.583
1983	4.585
1984	3.659
1985	3.31
1986	5.251
1987	4.35
1988	2.144
1989	3.353
1990	2.405
1991	9.229
1992	8.258
1993	6.71
1994	5.187
1995	3.015
1996	7.925
1997	5.291
1998	6.588
1999	3.891
2000	4.134
2001	3.438
2002	3.437
2003	3.181
2004	3.444
2005	3.411
2006	0.5239
2007	0.8973