Year	% of total
1971	63.48279787864978
1972	65.69151688312253
1973	66.85234351583048
1974	67.7345451626629
1975	67.98264881047797
1976	69.5941091253987
1977	69.75393276097765
1978	68.50233781424674
1979	68.71520614623708
1980	70.64920388709442
1981	69.34349856359646
1982	68.95647133061316
1983	71.0288029107909
1984	69.22029714149654
1985	70.19237961578739
1986	69.2615072062416
1987	70.20716660627897
1988	68.75744940516208
1989	67.1784992108628
1990	61.68943237216572
1991	59.47544771086311
1992	54.94125989929363
1993	61.616739985304015
1994	62.83147457845379
1995	68.85471623745077
1996	66.95607493451551
1997	68.90243617209417
1998	71.65304374759577
1999	70.47882818438893
2000	70.9001632755027
2001	69.7332787030279
2002	72.62938505642654
2003	75.27021054218902
2004	75.43884756721117
2005	81.02690630031807
2006	84.23232078028897
2007	84.97962141146131
2008	86.92784489419874
2009	87.26589082656166
2010	89.88459214472138
2011	87.59646004339511
2012	87.46447103862764
2013	87.50883462237242
2014	85.59641455996507