Year	Percent
1990	73.08
1991	73.2
1992	72.88
1993	72.92
1994	73.78
1995	74.54
1996	75.43
1997	75.36
1998	74.94
1999	74.88
2000	74.99
2001	75.6
2002	76.26
2003	75.9
2004	76.35
2005	77.24
2006	77.81
2007	77.99
2008	77.76
2009	77.39
2010	77.07
2011	77.27
2012	77.1
2013	77.51
2014	78.68
2015	78.73
2016	79.92
2017	80.93
2018	81.12
2019	80.89