Year	Percent
1990	71.53
1991	71.84
1992	71.99
1993	72.06
1994	72.14
1995	72.28
1996	72.41
1997	72.54
1998	72.64
1999	72.73
2000	72.79
2001	72.85
2002	72.9
2003	72.96
2004	73.04
2005	74.03
2006	73.94
2007	73.6
2008	74.92
2009	75.5
2010	76.18
2011	76.02
2012	76.22
2013	77.76
2014	78.14
2015	78.53
2016	78.78
2017	79.37
2018	78.79
2019	79.1