Year	Percent
1985	11.11
1986	10.68
1987	10.73
1988	13.08
1989	19.08
1990	20.51
1991	20.06
1992	16.15
1993	15.78
1994	18.52
1995	19.04
1996	24.95
1997	25.58
1998	27.52
1999	26.99
2000	27.8
2001	29.17
2002	30.75
2003	30.72
2004	30.54
2005	29.6
2006	27.75
2007	27.7
2008	27.43
2009	29.67
2010	30.2