Year	Percent
1990	76.32
1991	75.51
1992	75.38
1993	75.03
1994	75.52
1995	76.73
1996	78.17
1997	79.84
1998	80.85
1999	80.3
2000	80.45
2001	80.25
2002	80.31
2003	78.58
2004	78.35
2005	77.92
2006	78.09
2007	78.86
2008	80.04
2009	78.82
2010	78.01
2011	77.67
2012	78.06
2013	77.98
2014	77.88
2015	78.18
2016	77.97
2017	77.23
2018	77.77
2019	78.17