Year	Percent
1990	51.57
1991	51.58
1992	51.82
1993	52
1994	51.89
1995	52.18
1996	52.05
1997	52.25
1998	52.24
1999	52.38
2000	52.5
2001	52.58
2002	52.34
2003	53.01
2004	53.33
2005	53.17
2006	52.95
2007	52.85
2008	52.66
2009	52.73
2010	52.81
2011	52.87
2012	52.15
2013	51.8
2014	50.99
2015	50.17
2016	49.38
2017	48.57
2018	48.65
2019	48.73