Year	Percent
1990	78.41
1991	76.75
1992	77.85
1993	78.83
1994	79.63
1995	80.6
1996	80.12
1997	80.16
1998	80.02
1999	79.87
2000	79.72
2001	79.66
2002	79.62
2003	79.59
2004	80.31
2005	80.13
2006	79.89
2007	79.6
2008	79.28
2009	78.96
2010	78.62
2011	78.64
2012	77.62
2013	78.17
2014	76.61
2015	77.15
2016	77.78
2017	77.76
2018	77.73
2019	77.73