Year	Percent
1990	83.07
1991	82.97
1992	82.92
1993	80.75
1994	78.99
1995	77.46
1996	76.89
1997	75.56
1998	75.64
1999	76.97
2000	77.3
2001	77.21
2002	77.06
2003	77.97
2004	77.84
2005	78.77
2006	79.68
2007	79.89
2008	80.08
2009	80.12
2010	80.79
2011	81.22
2012	82.89
2013	83.29
2014	85.03
2015	85.8
2016	86.09
2017	86.82
2018	86.98
2019	86.98