Year	Percent
1990	75.71
1991	75.76
1992	75.83
1993	75.89
1994	75.91
1995	75.23
1996	74.52
1997	73.67
1998	72.67
1999	72.19
2000	71.69
2001	71.15
2002	70.6
2003	70.02
2004	69.69
2005	69.39
2006	69.07
2007	68.76
2008	68.46
2009	68.15
2010	67.84
2011	67.63
2012	67.42
2013	68.53
2014	68.39
2015	68.74
2016	70.31
2017	71.15
2018	70.44
2019	71.38