Year	Percent
1990	27.74
1991	25.65
1992	33.08
1993	20.39
1994	37.99
1995	48.16
1996	30.1
1997	37.32
1998	31.83
1999	29.25
2000	25.91
2001	25.4
2002	26.85
2003	26.31
2004	28.73
2005	26.98
2006	26.26
2007	30.11
2008	29.28
2009	31.65
2010	30.04