Year	Percent
1991	72.38
1992	71.97
1993	70.52
1994	70.51
1995	72.73
1996	72.79
1997	71.86
1998	73.68
1999	75.55
2000	76.85
2001	76.63
2002	74.71
2003	73.72
2004	73.3
2005	73.84
2006	74.45
2007	74.99
2008	73.83
2009	69.25
2010	69.24
2011	69.09
2012	69.89
2013	71.06
2014	72.53
2015	73.95
2016	75.43
2017	74.54
2018	73.26
2019	71.74
2020	69.43