Year	% of total
1960	80.67940552016985
1961	82.15767634854772
1962	83.87755102040816
1963	84.9340866290019
1964	87.2340425531915
1965	84.52380952380952
1966	83.73570520965691
1967	80.16627078384798
1968	83.5881753312946
1969	83.36501901140684
1970	82.66405484818804
1971	87.11923411662316
1972	84.13312693498452
1973	82.76385725132877
1974	78.19293478260869
1975	79.70918704560475
1976	82.19435736677116
1977	83.4508952794357
1978	81.00832109642683
1979	78.80434782608697
1980	78.21552723059096
1981	76.95749440715883
1982	77.9445727482679
1983	76.45150827116444
1984	70.53032708796444
1985	66.76904176904176
1986	72.79635258358662
1987	61.48564294631711
1988	67.8729037952339
1989	61.37434192297035
1990	64.05915636363636
1991	78.06997226074897
1992	65.5856719367589
1993	68.63416464891041
1994	58.16544744744745
1995	52.87452464788732
1996	56.77599431818182
1997	54.48056655665566
1998	55.1406712473573
1999	51.9922933467742
2000	53.62965599617774
2001	53.21807852193995
2002	52.7015232397607
2003	53.3534247828075
2004	53.31043802014892
2005	53.24598098530683
2006	51.24963855421687
2007	49.890342577487765
2008	48.32629689390883
2009	46.08230769230769
2010	41.935298833819246
2011	41.91671850699844
2012	40.600892053973006
2013	42.57391109450877
2014	41.1472251127298
2015	45.77879339400067
2016	45.511783373577096