Year	Percent
1991	55.16
1992	56.51
1993	56.29
1994	56.34
1995	56.24
1996	55.17
1997	56.18
1998	55.51
1999	55.85
2000	54.87
2001	53.89
2002	52.98
2003	50.88
2004	49.33
2005	49.39
2006	48.48
2007	47.45
2008	48.44
2009	48.94
2010	48.24
2011	46.44
2012	45.49
2013	48.59
2014	48.2
2015	49.21
2016	47.63
2017	50.3
2018	51.89
2019	51.84