Year	Percent
1991	54.92
1992	55.02
1993	54.98
1994	55.01
1995	55.25
1996	55.43
1997	55.48
1998	55.56
1999	55.75
2000	55.7
2001	56.24
2002	56.84
2003	57.06
2004	56.87
2005	56.57
2006	56.12
2007	55.7
2008	55.93
2009	56.31
2010	56.1
2011	55.49
2012	55.43
2013	55.35
2014	55.26
2015	55.23
2016	55.09
2017	54.92
2018	54.71
2019	54.53
2020	53.08