Year	Percent
1990	52.46
1991	52.46
1992	52.41
1993	52.27
1994	52.26
1995	52.04
1996	51.94
1997	52
1998	51.95
1999	51.86
2000	51.88
2001	51.34
2002	50.8
2003	50.29
2004	49.79
2005	49.31
2006	48.85
2007	48.43
2008	48.02
2009	47.64
2010	47.28
2011	46.92
2012	46.58
2013	46.54
2014	46.51
2015	46.49
2016	46.45
2017	46.42
2018	46.52
2019	46.54