Year	% of total
1971	94.38444924406048
1972	94.89120151371807
1973	93.80831212892281
1974	98.34834834834835
1975	97.72727272727273
1976	96.61229611041405
1977	98.28159645232816
1978	98.60710854947166
1979	98.3030303030303
1980	99.17920656634746
1981	99.0506329113924
1982	98.80088355948249
1983	99.18332863981976
1984	98.29896907216494
1985	97.30049727681744
1986	98.79813042510573
1987	97.52931323283082
1988	99.05805459438677
1989	99.33530280649926
1990	99.20839786611599
1991	98.17578772802653
1992	98.9520727384805
1993	99.03396226415094
1994	99.43246311010215
1995	99.49145912113705
1996	99.15478743534754
1997	99.48131557232112
1998	99.20748486516236
1999	99.09972991897568
2000	99.17893544733862
2001	99.31530898876404
2002	99.20614812938096
2003	98.23737821080603
2004	98.34170854271356
2005	98.52302345786272
2006	99.00467039277238
2007	99.33037338962079
2008	99.5195989695746
2009	98.8460529766588
2010	95.93818714879062
2011	97.84809359277445
2012	97.09872100105198
2013	96.322289320494
2014	95.68817372285581
2015	96.07643830046757