Year	Percent
1985	29.34
1986	34.3
1987	31.44
1988	26.42
1989	28.24
1991	41.44
1992	33.5
1994	23.32
1995	28.47
1996	28.47
1998	28.44
1999	29.85
2000	28.98
2001	27.47
2002	24.78
2003	19.09
2004	17.54
2005	18.82
2006	15.1
2007	18.73