Year	Percent
1990	90.76
1991	90.65
1992	90.13
1993	89.59
1994	89.03
1995	88.45
1996	87.84
1997	87.21
1998	86.56
1999	85.89
2000	85.19
2001	84.47
2002	83.72
2003	82.96
2004	82.17
2005	81.37
2006	80.54
2007	80.51
2008	80.43
2009	80.31
2010	80.14
2011	79.91
2012	79.62
2013	79.27
2014	78.83
2015	78.93
2016	79
2017	79.07
2018	79.15
2019	79.24