Year	Percent
1990	24.64
1991	28.54
1992	32.84
1993	38.96
1994	41.14
1995	41.68
1996	44.59
1997	41.17
1998	41.26
1999	41.06
2000	40.17
2001	39.96
2002	39.01
2003	39.05
2004	37.38
2005	37.03
2006	34.96
2007	33.22
2008	34.77
2009	38.23
2010	35.87