Year	Percent
1990	88.64
1991	88.81
1992	89.04
1993	89.27
1994	89.47
1995	89.62
1996	89.72
1997	89.84
1998	89.9
1999	89.99
2000	89.09
2001	88.1
2002	87.03
2003	85.85
2004	84.58
2005	83.21
2006	84.3
2007	85.33
2008	86.3
2009	87.2
2010	88.05
2011	88.85
2012	89.6
2013	90.3
2014	90.96
2015	91.58
2016	92.17
2017	92.29
2018	92.38
2019	92.48