Year	Percent
1998	90.30381
1999	89.40209
2000	88.64872
2001	88.06232
2002	87.86203
2003	86.61548
2004	83.66881
2005	82.67975
2006	83.2534
2007	82.70282
2008	81.63546
2009	79.69145
2010	78.7725
2011	79.50507
2012	80.18142
2013	79.78606
2014	80.53178
2015	81.31771
2016	80.938
2017	81.0319