Year	Percent
1990	10.86
1991	11.42
1992	15.3
1993	15.53
1994	32.92
1995	32.06
1996	36.95
1997	34.41
1998	34.55
1999	36.92
2000	23.36
2001	23.69
2002	23.71
2003	24.96
2004	22.36
2005	22.11
2006	21.28
2007	20.32
2008	19.87
2009	27.14
2010	25.91