Year	Percent
1991	54.46
1992	53.82
1993	54.31
1994	55.61
1995	55.87
1996	55.48
1997	55.82
1998	56.59
1999	56.51
2000	56.86
2001	54.66
2002	52.34
2003	50.5
2004	50.3
2005	50.45
2006	50.97
2007	49.83
2008	47.95
2009	43.65
2010	41.62
2011	41.91
2012	43.19
2013	43.2
2014	44.33
2015	45.39
2016	46.38
2017	47.45
2018	47.45
2019	48.03