Year	Percent
1990	89.38
1991	89.34
1992	89.35
1993	89.61
1994	89.85
1995	89.79
1996	89.7
1997	89.59
1998	89.53
1999	89.97
2000	89.34
2001	89.23
2002	88.48
2003	90.5
2004	88.81
2005	87.81
2006	85.71
2007	85.57
2008	85.31
2009	86.94
2010	88.33
2011	89.67
2012	89.69
2013	89.46
2014	89.72
2015	89.27
2016	89.32
2017	89.21
2018	89.57
2019	90.14