Year	%
1971	58.9834
1972	64.03885
1973	70.48968
1975	74.32097
1977	84.51702
1980	69.89566
1982	69.79577
1983	72.47913
1984	59.16438
1985	69.77554
1986	66.22531
1987	68.00547
1999	76.43003
2000	77.94121
2001	71.62414
2002	77.36294
2003	83.12708
2004	81.33119
2005	79.67677
2006	86.3267
2007	83.16274
2008	84.79774
2009	86.32853
2010	92.88982
2012	79.87108
2013	85.06289
2014	77.9405
2015	78.93006
2016	78.305