Year	% of total
1971	99.07280120574943
1972	99.17049302532138
1973	99.0148284069022
1974	98.92776250365488
1975	99.01211543833621
1976	99.20415770316382
1977	99.07467204662355
1978	99.05053476372287
1979	98.97584927516854
1980	99.2021213683867
1981	99.27250895092449
1982	99.2927420727965
1983	99.41339782783764
1984	99.4384974573492
1985	99.50571038337674
1986	99.5482825167133
1987	98.44765254311733
1988	98.71258923695336
1989	98.83152455597714
1990	98.76920404257348
1991	99.37018628113901
1992	99.64271262536452
1993	99.75337386439637
1994	99.7905292470185
1995	99.77582459727067
1996	99.7731858541253
1997	99.80444017776546
1998	99.71909612421459
1999	99.62792001658565
2000	99.67868430652231
2001	99.70763948052496
2002	99.7209951932265
2003	99.72154385427025
2004	99.27219718140529
2005	97.51125459959694
2006	96.82694990425718
2007	97.167016659733
2008	97.84255721639589
2009	97.58238974252933
2010	97.55356734883644
2011	97.67302487517165
2012	97.57448177236436
2013	96.68062347520782
2014	95.98417678330149