Year	Percent
1971	1.351
1972	0.7393
1973	7.274
1974	5.971
1975	6.585
1976	14.41
1977	7.555
1978	7.771
1979	6.991
1980	4.789
1981	7.075
1982	7.079
1983	6.456
1984	3.538
1985	7.204
1986	4.757
1987	4.369
1988	4.888
1989	3.662
1990	5.859
1991	4.32
1992	7.199
1993	5.515
1994	8.725
1995	9.824
1996	12.38
1997	7.701
1998	6.564
1999	12.21
2000	8.494
2001	8.082
2002	8.678
2003	8.678
2004	7.58
2005	5.207
2006	12.78
2007	4.44