Year	% of total
1971	77.90697674418605
1972	78.50467289719626
1973	77.88461538461539
1974	85.71428571428571
1975	85.22727272727273
1976	90.20979020979021
1977	88.53503184713377
1978	87.93103448275862
1979	88.08290155440415
1980	93.54838709677419
1981	96.04743083003953
1982	98.4567901234568
1983	99.16434540389972
1984	98.96373056994818
1985	99.30232558139535
1986	99.81515711645102
1987	98.93617021276596
1988	96.23287671232876
1989	99.86033519553072
1990	99.88610478359908
1991	96.56652360515021
1992	94.69525959367945
1993	93.35476956055734
1994	91.98019801980199
1995	96.90635451505017
1996	96.72399672399672
1997	90.84687767322498
1998	90.48
1999	95.46684709066305
2000	98.37251356238697
2001	99.03588644884842
2002	99.81158737635421
2003	99.82355535950596
2004	99.42100909842844
2005	99.36833793920252
2006	99.5269286754003
2007	99.67765042979943
2008	99.67994310099573
2009	99.58266452648475
2010	99.9064837905237
2011	99.94272623138602
2012	99.46509009009009
2013	99.71566676144441
2014	99.78930734790625
2015	99.80017128175848