Year	Percent
1990	73.83
1991	73.92
1992	74.05
1993	74.21
1994	74.38
1995	74.54
1996	74.71
1997	74.85
1998	74.98
1999	75.06
2000	75.08
2001	75.08
2002	75.04
2003	74.97
2004	74.89
2005	74.79
2006	74.67
2007	74.54
2008	74.1
2009	74.64
2010	76.57
2011	77.23
2012	76.82
2013	76.39
2014	75.96
2015	73.95
2016	73.3
2017	72.92
2018	70.74
2019	70.69