Year	Percent
1990	68.71
1991	69.32
1992	69.82
1993	69.33
1994	68.82
1995	68.34
1996	65.91
1997	66.06
1998	65.12
1999	65.03
2000	64.36
2001	62.96
2002	57.31
2003	55.52
2004	55.07
2005	53.46
2006	54.43
2007	54.19
2008	53.9
2009	53.73
2010	54.94
2011	54.13
2012	54.61
2013	54.48
2014	54.78
2015	54.45
2016	53.72
2017	55
2018	55.05
2019	55.13
2020	55.04