Year	Percent
1990	76.39
1991	76.03
1992	75.44
1993	74.96
1994	74.75
1995	74.49
1996	74.63
1997	74.81
1998	74.63
1999	74.94
2000	75.17
2001	74.72
2002	74.87
2003	74.89
2004	74.89
2005	75.22
2006	75.57
2007	75.4
2008	75.68
2009	75.49
2010	75.25
2011	75.35
2012	75.87
2013	76.25
2014	76.55
2015	76.79
2016	77.16
2017	77.41
2018	77.73
2019	78.01