Year	% of total
1960	95.52018062066236
1961	95.861883084396
1962	96.43236550830402
1963	95.89151318133023
1964	96.69442997779076
1965	95.82039494328876
1966	95.15636319638
1967	95.70259703589397
1968	95.50743415058875
1969	95.53945897880669
1970	89.7415279220509
1971	89.92143247490793
1972	89.79686784546313
1973	90.26813077049546
1974	89.93530509343462
1975	88.2559046833689
1976	90.16324604147741
1977	88.0351920371777
1978	87.26473416849585
1979	86.36570693714782
1980	83.8755071961136
1981	77.75584647501749
1982	76.61918614421526
1983	72.29762216248666
1984	67.52500997564981
1985	64.3392191218306
1986	61.28573803565711
1987	60.418524016003005
1988	59.39941238744083
1989	58.848211733623465
1990	58.15395849174819
1991	57.944784449867356
1992	56.159705781616424
1993	54.19402550859748
1994	53.313483029919084
1995	53.57382198022184
1996	53.84750116460191
1997	52.90067538117532
1998	54.79426486535874
1999	54.01870151378214
2000	52.80593885211409
2001	53.400578129570896
2002	52.81353407472164
2003	52.693992518836986
2004	52.415038540393454
2005	52.29710793985124
2006	51.8924519811957
2007	51.685506010110984
2008	50.84346549626092
2009	50.851682588665255
2010	49.83637832155579
2011	48.67698651006357
2012	49.01202707006454
2013	48.54358131131076
2014	46.22592306123835
2015	46.48797087223635