Year	Percent
1990	82.41
1991	82.28
1992	82.04
1993	81.19
1994	78.71
1995	79.56
1996	79.5
1997	79.85
1998	79.38
1999	80.55
2000	79.85
2001	79
2002	79.82
2003	79.18
2004	79.98
2005	79.7
2006	80.52
2007	80.23
2008	79.45
2009	78.72
2010	77.94
2011	77.56
2012	76.9
2013	76.3
2014	76.42
2015	76.86
2016	77.43
2017	77.89
2018	78.2
2019	79.01