Year	Percent
1990	74.53
1991	74.59
1992	74.45
1993	74.58
1994	75.02
1995	75.3
1996	75.84
1997	76.42
1998	74.96
1999	74.61
2000	75.25
2001	75.32
2002	75.68
2003	75.43
2004	75.93
2005	76.03
2006	76.39
2007	76.45
2008	76.56
2009	75.95
2010	76.42
2011	76.88
2012	77.06
2013	77.35
2014	78.39
2015	78.62
2016	78.92
2017	79.2
2018	79.35
2019	79.15