Year	%
1971	48.80567
1972	66.52556
1973	82.05096
1974	81.16702
1975	84.47203
1976	95.84855
1977	99.0932
1978	97.10738
1980	99.34511
1982	95.22115
1983	98.23717
1986	83.55263
1988	81.63298
1992	71.74586
1993	69.90687
1995	66.32972
2001	73.51923
2002	68.66047
2003	87.68047
2004	70.10854
2007	70.05559
2008	71.22435
2009	75.79751
2010	77.27496
2011	76.43519