Year	Percent
1990	74.41
1991	74.25
1992	74.07
1993	73.87
1994	73.65
1995	73.45
1996	73.25
1997	73.13
1998	73.01
1999	72.91
2000	71.8
2001	70.63
2002	69.39
2003	68.1
2004	66.78
2005	65.45
2006	66.62
2007	67.79
2008	68.93
2009	69.99
2010	70.95
2011	71.83
2012	72.61
2013	73.33
2014	74.01
2015	74.67
2016	75.3
2017	75.06
2018	74.81
2019	74.56