Year	Percent
1990	78.65
1991	79.23
1992	78.62
1993	78.56
1994	78.99
1995	79.3
1996	79.26
1997	79.47
1998	79.52
1999	79.73
2000	79.95
2001	80.5
2002	81.12
2003	80.92
2004	81.16
2005	81.21
2006	81.54
2007	81.81
2008	81.8
2009	82.34
2010	81.74
2011	82.48
2012	82.89
2013	83.68
2014	83.56
2015	83.63
2016	83.61
2017	83.92
2018	84.13
2019	84.15