Year	Percent
1990	72.86
1991	73.3
1992	73.7
1993	73.28
1994	72.92
1995	72.68
1996	70.66
1997	71.63
1998	70.39
1999	70.03
2000	69.61
2001	68.2
2002	63.97
2003	63.26
2004	63.66
2005	62.05
2006	63.41
2007	62.78
2008	62.62
2009	62.79
2010	64.66
2011	63.89
2012	64.68
2013	64.83
2014	65.55
2015	65.91
2016	65.54
2017	67.4
2018	67.93
2019	68.75