Year	Percent
1990	57.58
1991	57.67
1992	57.77
1993	56.83
1994	55.88
1995	54.91
1996	53.96
1997	53.02
1998	52.04
1999	51
2000	49.88
2001	51.64
2002	51.16
2003	50.27
2004	51.07
2005	50.38
2006	52.32
2007	53.79
2008	55.13
2009	54.33
2010	53.4
2011	52.53
2012	53.07
2013	53.86
2014	54.15
2015	54.18
2016	53.45
2017	55.46
2018	55.46
2019	56.75
2020	54.8