Year	% of total
1989	93.6
1991	90.3
1994	82.6
1995	80.9
1996	79
1997	72.6
1998	74.1
1999	66.6
2000	70.7
2001	81.1
2002	88.7
2003	88.1
2004	75.1
2005	82.4
2006	78.3
2007	88.4
2008	85
2009	87.1
2010	87.7
2011	89
2012	87.4
2013	90.8
2014	90.3
2015	98
2017	94.8