Year	Percent
1990	82.98
1991	83.78
1992	84.23
1993	84.29
1994	84.18
1995	83.8
1996	83.35
1997	82.81
1998	82.41
1999	82.61
2000	82.12
2001	81.66
2002	81.29
2003	81.06
2004	80.77
2005	80.66
2006	80.63
2007	82.05
2008	80.4
2009	79.42
2010	78.71
2011	80.19
2012	80.58
2013	81.05
2014	81.17
2015	80.98
2016	81.89
2017	82.46
2018	83.74
2019	83.06