Year	% of total
1960	35.59502664298401
1961	42.012620391896384
1962	31.573033707865168
1963	52.824504142606074
1964	37.0253875533588
1965	43.99353926912982
1966	42.11853720050441
1967	38.351312188053456
1968	45.77566320645906
1969	43.95253891298801
1970	35.17337353589238
1971	26.684388099376342
1972	28.50662634528151
1973	20.949698189134807
1974	24.901684351116717
1975	37.79043717595852
1976	45.8075808127769
1977	41.68247021638706
1978	42.966952039031575
1979	45.68421987390107
1980	48.756176154672396
1981	51.1328172496251
1982	53.355679421512505
1983	41.47804146707134
1984	43.85718485610688
1985	35.199742832929076
1986	29.91056808162237
1987	41.976867404685144
1988	60.2501665001665
1989	34.46891092152794
1990	40.22730827381263
1991	37.650632407130765
1992	39.452347717620505
1993	45.999078690656845
1994	39.05210607627584
1995	41.208389857038505
1996	42.66724294237946
1997	38.545539033457246
1998	38.03660535749671
1999	29.781003091721058
2000	24.718624421639102
2001	19.564066001222244
2002	26.030139103554866
2003	25.13141889729053
2004	30.580366030073392
2005	24.42700486551903
2006	25.096001678965845
2007	18.715480428904037
2008	16.767631968873793
2009	18.45779520768741
2010	24.523692284383166
2011	22.815866220852424
2012	24.161155092360623
2013	24.742456923474105
2014	16.131336743886997
2015	25.64948831665922