Year	Percent
1990	36.42
1991	36.07
1992	35.76
1993	34.62
1994	23.29
1995	34.26
1996	35.46
1997	35.39
1998	33.97
1999	33.39
2000	31.95
2001	31.23
2002	20.1
2003	20.17
2004	19.46
2005	19.5
2006	20.29
2007	21.06
2008	21.7
2009	21.7
2010	22.1
2011	21.84
2012	21.37
2013	17.5
2014	17.7