Year	Percent
1976	12.66
1977	12.32
1978	10.64
1979	10.93
1981	10.74
1982	13.77
1983	14.52
1984	13.06
1985	13.74
1986	13.14
1987	11.95
1988	10
1990	10.17
1991	10.61
1992	9.86
1993	12.68
1995	9.09
1996	9.33
1997	9.33
1998	8.86
1999	9.86
2000	7.89
2002	9.2
2003	8.14
2004	7.95
2005	7.87
2006	7.69
2007	9.57
2008	8.51