Year	Percent
1982	59.51
1983	58.51
1984	56.63
1990	67.59
1991	66.23
1992	66.8
1993	69.42
1994	70.6
1995	71.99
1996	73.9
1997	73.21
1998	74.07
1999	75.32
2000	76.21
2001	76.88
2002	78.56
2003	76.32
2004	75.63
2005	75.31
2006	75.13
2008	74.36
2009	75.2
2010	72.27
2011	70.91
2012	72.62
2013	72.73
2014	72.84
2017	77.31