Year	Percent
1990	67.48
1991	67.56
1992	67.65
1993	67.95
1994	67.66
1995	67.49
1996	67.21
1997	66.85
1998	66.81
1999	66.67
2000	66.58
2001	66.6
2002	66.54
2003	66.41
2004	66.45
2005	66.59
2006	66.64
2007	66.76
2008	66.76
2009	66.72
2010	66.64
2011	66.55
2012	66.43
2013	66.3
2014	66.13
2015	65.95
2016	65.77
2017	65.59
2018	65.38
2019	65.13