Year	Percent
1990	33.69
1991	33.04
1992	32.4
1993	31.76
1994	31.12
1995	30.48
1996	29.84
1997	29.2
1998	28.56
1999	27.91
2000	27.21
2001	26.84
2002	26.47
2003	26.1
2004	25.73
2005	25.36
2006	25.36
2007	25.36
2008	25.36
2009	25.36
2010	25.36
2011	25.36
2012	25.36
2013	25.36
2014	25.36
2015	25.36