Year	% of total
1960	5.524733087789641
1961	5.646630236794172
1962	3.1813923174060044
1963	2.9285036149857593
1964	3.8388220600801946
1965	3.562356175846508
1966	3.7914164998888147
1967	3.98479048377566
1968	4.372395958047987
1969	4.8676738220010085
1970	4.639436220408659
1971	3.370722971062306
1972	3.2671860101110055
1973	2.605145083914238
1974	7.4177837162191285
1975	6.554859402818739
1976	6.627657346318987
1977	6.110053705432371
1978	6.210224491223163
1979	5.9000695034365584
1980	5.427683390385787
1981	5.3919458359423915
1982	5.67553848658692
1983	5.487267454533392
1984	4.98278088678433
1985	3.9002172822998498
1986	3.0078006604240115
1987	2.12814488720604
1988	1.7672494829855236
1989	2.0559959750343344
1990	2.302203037196912
1991	2.169469003935197
1992	1.4843583072533715
1993	1.4831287216055282
1994	1.3878171192027229
1995	1.5844448945343017
1996	1.5822874065717105
1997	1.1911346721504499
1998	0.9337551725729288
1999	0.8491015435084739
2000	0.8500743338543056
2001	0.9114217555124519
2002	1.0757417164369465
2003	0.7529942970088763
2004	0.6086419266211829
2005	1.2441591087248791
2006	1.313985914827244
2007	1.1906378740549595
2008	1.6694573235200947
2009	1.4502509119490519
2010	2.413606120696138
2011	2.2878455497485297
2012	1.5093107348232633
2013	2.5678929256753236
2014	2.019221473914865
2015	2.695064136104901