Year	Percent
1990	54.77
1991	54.7
1992	54.49
1993	54.53
1994	54.5
1995	54.54
1996	53.6
1997	52.69
1998	51.85
1999	52.02
2000	52.07
2001	51.78
2002	51.39
2003	50.8
2004	49.55
2005	48.36
2006	47.33
2007	46.31
2008	46.48
2009	44.83
2010	44.98
2011	45.13
2012	45.29
2013	45.5
2014	45.75
2015	46.02
2016	46.21
2017	46.44
2018	46.65
2019	46.84