Year	Percent
1990	37.51
1991	36.93
1992	36.35
1993	35.77
1994	35.18
1995	34.6
1996	34.02
1997	33.44
1998	32.86
1999	32.28
2000	31.69
2001	31.11
2002	30.53
2003	29.95
2004	29.37
2005	28.79
2006	28.2
2007	27.62
2008	27.04
2009	26.46
2010	25.88
2011	25.88
2012	25.88
2013	25.88
2014	25.88
2015	25.88