Year	Percent
1990	53.06
1991	53.04
1992	53.05
1993	53.06
1994	53.06
1995	53.04
1996	53
1997	53.47
1998	53.96
1999	54.49
2000	55.07
2001	55.79
2002	56.53
2003	57.29
2004	58.06
2005	58.8
2006	58.01
2007	57.18
2008	54.87
2009	55
2010	54.1
2011	53.73
2012	53.4
2013	53.1
2014	52.79
2015	53.92
2016	55.36
2017	56.33
2018	56.52
2019	56.53