Year	Percent
1990	79.82
1991	79.89
1992	80.41
1993	80.53
1994	79.49
1995	79.58
1996	80.22
1997	80.29
1998	81.05
1999	81.05
2000	80.56
2001	81.14
2002	81.22
2003	81.25
2004	80.93
2005	80.87
2006	81.29
2007	81.68
2008	82.35
2009	82.49
2010	81.27
2011	82
2012	82.22
2013	82.38
2014	82.92
2015	83.38
2016	83.93
2017	83.96
2018	84.17
2019	84.21