Year	Percent
1990	86.18
1991	85.93
1992	86.59
1993	86.01
1994	85.85
1995	86.51
1996	86.87
1997	86.99
1998	87.87
1999	87.49
2000	87.32
2001	87.8
2002	88.33
2003	88.06
2004	88.24
2005	88.49
2006	88.37
2007	88.92
2008	89.79
2009	90.01
2010	88.35
2011	89.04
2012	89.44
2013	89.22
2014	89.98
2015	90.23
2016	90.6
2017	90.42
2018	90.82
2019	91.28