Year	Percent
1991	51.18
1992	49.25
1993	49.59
1994	50.17
1995	48.8
1996	49.46
1997	50.03
1998	54.05
1999	52.75
2000	52.52
2001	52.31
2002	51.73
2003	51.96
2004	51.77
2005	52.05
2006	52.62
2007	52.8
2008	53.06
2009	52.52
2010	52.02
2011	52.02
2012	51.37
2013	52.52
2014	51.66
2015	52.3
2016	52.67
2017	52.84
2018	50.65
2019	50.26
2020	48.65