Year	Percent
1992	18
1993	16.3
1994	15
1995	17.03
1996	18.12
1997	18.41
1998	19.08
2000	16.2
2002	17.14
2003	17.12
2004	17
2005	19.15
2006	17.72
2007	14.48
2008	12.44
2009	11.22
2011	11.01
2013	15.38