Year	Percent
1990	67.19
1991	67.28
1992	67.51
1993	68.23
1994	68.2
1995	67.83
1996	67.57
1997	67.44
1998	67.33
1999	67.25
2000	67.12
2001	67.05
2002	66.73
2003	66.64
2004	66.38
2005	66.04
2006	65.89
2007	65.67
2008	65.52
2009	65.61
2010	65.59
2011	65.67
2012	65.6
2013	65.58
2014	65.54
2015	65.58
2016	65.73
2017	65.79
2018	65.87
2019	65.88