Year	Percent
1990	80.51
1991	82.61
1992	81.97
1993	82.99
1994	83.5
1995	83.87
1996	84.04
1997	84.05
1998	83.93
1999	84.21
2000	84.62
2001	85.15
2002	85.4
2003	86.05
2004	86.38
2005	87.06
2006	87.71
2007	87.73
2008	87.96
2009	87.79
2010	88.67
2011	88.37
2012	88.5
2013	88.27
2014	88.64
2015	88.81
2016	89.17
2017	89.64
2018	89.89
2019	90.31