Year	Percent
1991	36.21
1992	35.87
1993	34.76
1994	35.93
1995	36.26
1996	35.94
1997	34.79
1998	29.52
1999	29.88
2000	31.23
2001	31.21
2002	32.25
2003	31.63
2004	32.36
2005	31.53
2006	29.31
2007	27.96
2008	25.07
2009	23.65
2010	23.52
2011	23.63
2012	24.77
2013	24.65
2014	26.32
2015	25.65
2016	25.9
2017	25.86
2018	24.95
2019	25.33