Year	% of total
1960	98.86483632523759
1961	98.82088714205503
1962	99.04816186947848
1963	98.98469062300659
1964	99.19225341832514
1965	98.73092894135212
1966	98.65330271988697
1967	98.59862395002321
1968	98.84731670445956
1969	99.13595062575004
1970	99.00730596599286
1971	99.59683485272437
1972	99.48461953588776
1973	99.10624153637818
1974	98.82781112634116
1975	82.72820814346612
1976	78.35027481272415
1977	73.52194414218354
1978	74.29537767756483
1979	76.96561024949426
1980	75.27452863950576
1981	72.96557511338435
1982	67.46768578174397
1983	52.45522373672136
1984	47.245297075805546
1985	37.42867807817416
1986	30.20947224102324
1987	31.114926115487666
1988	31.72866859825537
1989	36.94394186342091
1990	37.80515563648779
1991	38.3235467648133
1992	37.43873407085842
1993	38.54113147228407
1994	41.32125986459399
1995	41.856194569889546
1996	40.59996273523384
1997	37.55538716430562
1998	42.0420347243375
1999	39.337379747139124
2000	39.63128073163954
2001	38.42377063776743
2002	38.91819765502416
2003	40.95690573353598
2004	41.058409303759205
2005	40.93152411065349
2006	39.85275288092189
2007	39.44794808518417
2008	38.6286685091466
2009	39.80469010979222
2010	40.26408619568809
2011	35.022580717639926
2012	35.95153208120459
2013	31.936127744510976
2014	33.47738524796509
2015	39.21464312417323