Year	Percent
1990	24.11
1991	23.64
1992	33.91
1993	43.46
1994	25.89
1995	53.03
1996	40.54
1997	42.17
1998	49.07
1999	49.36
2000	52.65
2001	52.33
2002	50.46
2003	49.54
2004	49.73
2005	36.86
2006	36.64
2007	35.79
2008	35.76
2009	38.13
2010	39.57