Year	% of total
1960	3.164284946814226
1961	5.388447169269087
1962	10.870988867059594
1963	8.23647526740549
1964	12.155388471177945
1965	18.062035052326316
1966	13.580509036864036
1967	21.09617373319545
1968	23.830521053895353
1969	19.9707894534553
1970	27.227678809299682
1971	22.237557846878296
1972	17.36288007067658
1973	33.18794607454401
1974	36.03201958139767
1975	37.472289215328026
1976	48.248081124993
1977	29.131827940748096
1978	29.34234087579359
1979	25.377496346809547
1980	35.19217036236794
1981	33.09029419251609
1982	25.823304494916567
1983	21.142678846920557
1984	9.733629112830847
1985	6.167158903651576
1986	4.824999220139127
1987	4.853475709998039
1988	5.005628355365699
1989	6.207880434782609
1990	5.690250386889409
1991	6.5628857052388065
1992	9.144224633056798
1993	6.140029207599122
1994	6.531304769362718
1995	8.830527307422885
1996	8.02930233899576
1997	7.456105568684674
1998	9.048461156614545
1999	11.87590180579779
2000	10.219942875507535
2001	10.568634770259196
2002	11.917871597260719
2003	9.327939124723587
2004	8.616962826945043
2005	8.436836013750455
2006	8.06172229702756
2007	6.1317457319961965
2008	5.788833936805819
2009	6.592683703990489
2010	5.551756503083936
2011	5.0395667042839065
2012	5.212252757346687
2013	4.890120627476061
2014	5.135861559780178
2015	6.2064422301578155