Year	Percent
1995	50.5
1996	46.59
1997	44.24
1998	41.81
1999	40.89
2000	38.28
2001	35.57
2002	35.83
2003	36.23
2004	37.97
2005	38.77
2006	40.65
2007	46.93
2008	49.95
2009	52.5
2010	53.6