Year	Percent
1991	29.25
1992	28.94
1993	27.52
1994	25.64
1995	22.9
1996	22.9
1997	22.9
1998	21.3
1999	19.09
2000	19.09
2001	20.21
2002	20.21
2003	20.21
2004	19.39
2005	19.11
2006	18.13
2007	18.03
2008	18.08
2009	17.49
2010	16.98
2011	17.14
2012	19.19
2013	17.21
2014	16.89