Year	Percent
1991	55.17
1992	55.28
1993	55.28
1994	55.2
1995	55.06
1996	55.24
1997	55.26
1998	54.75
1999	54.16
2000	53.61
2001	53.22
2002	52.75
2003	52.28
2004	51.76
2005	51.13
2006	50.78
2007	50.34
2008	51.54
2009	52.31
2010	53.22
2011	54.42
2012	54.87
2013	55.19
2014	55.48
2015	49.77
2016	49.79
2017	49.85
2018	49.69
2019	49.4