Year	Percent
1990	74.53
1991	74.92
1992	75.21
1993	75.3
1994	75.29
1995	75.15
1996	74.99
1997	74.95
1998	74.75
1999	74.83
2000	74.61
2001	74.47
2002	74.3
2003	74.13
2004	73.97
2005	73.86
2006	73.84
2007	73.89
2008	73.99
2009	73.96
2010	73.99
2011	74.05
2012	75.16
2013	75.41
2014	77.89
2015	78.59
2016	79
2017	79.09
2018	79.7
2019	79.59