Year	%
1971	33.8977
1972	45.49844
1985	63.64812
1986	67.67924
1997	66.80381
1998	67.2381
1999	64.19799
2000	68.50111
2001	75.88154
2002	78.36171
2003	73.6773
2004	74.30959
2005	82.1585
2006	76.25178
2007	80.4239
2008	84.72619
2009	87.70262
2010	85.01314
2011	85.60718
2012	84.71093
2013	84.90076
2014	86.5959
2015	87.52957