Year	Percent
1990	85.09
1991	85.09
1992	84.51
1993	83.9
1994	83.27
1995	82.62
1996	81.96
1997	81.28
1998	80.58
1999	79.87
2000	79.13
2001	78.41
2002	77.66
2003	76.9
2004	76.13
2005	75.33
2006	74.53
2007	73.86
2008	73.16
2009	72.4
2010	71.6
2011	70.77
2012	69.89
2013	68.96
2014	67.97
2015	67.96
2016	67.93
2017	67.9
2018	67.85
2019	67.79