Year	Percent
1990	75.77
1991	75.44
1992	75.79
1993	75.75
1994	76.04
1995	76.22
1996	76.4
1997	76.7
1998	76.65
1999	76.56
2000	76.43
2001	75.93
2002	75.42
2003	74.78
2004	74.35
2005	74.26
2006	74.37
2007	74.11
2008	74.04
2009	73.3
2010	72.55
2011	71.96
2012	72.12
2013	71.67
2014	71.58
2015	71.55
2016	71.93
2017	72.37
2018	72.64
2019	73.11