Year	Percent
1990	73.08
1991	73.67
1992	72.38
1993	72
1994	72.19
1995	71.98
1996	72.26
1997	72.53
1998	73.22
1999	73.78
2000	74.07
2001	74.95
2002	75.74
2003	76.52
2004	77.77
2005	77.51
2006	77.85
2007	77.54
2008	78.09
2009	77.19
2010	76.85
2011	76.86
2012	77.83
2013	77.13
2014	76.96
2015	76.75
2016	77.46
2017	77.87
2018	77.91
2019	78.16