Year	Percent
1980	10.99
1985	12.44
1986	7.48
1988	10.98
1989	9.54
1990	10.09
1991	8.3
1992	8.44
1993	11.77
1994	8.45
1995	8.69
1996	8.38
1997	9.52
1998	7.94
1999	8.15
2000	9.05
2001	8.11
2002	7.44
2003	8.32
2004	7.78
2006	8.45
2007	8.3