Year	% of total
1960	13.864784354358244
1961	17.375974266980084
1962	16.664735866543097
1963	17.702089518794466
1964	16.84258142340169
1965	12.044664103972176
1966	12.466527819101458
1967	12.54973474801061
1968	13.017938103686182
1969	15.58631859021324
1970	9.723726977248104
1971	13.119636905184029
1972	11.536732929991357
1973	10.315047224738
1974	10.043406675647358
1975	8.00961841238943
1976	10.446690015502096
1977	6.657201028718389
1978	6.64861852058285
1979	5.913376620145782
1980	7.021634615384616
1981	10.322870804336505
1982	9.01621877589677
1983	10.07099971409511
1984	11.30499483954588
1985	10.927712495999268
1986	9.343520476612776
1987	9.921912735469329
1988	8.272238260400009
1989	9.765028989929814
1990	14.212106458941903
1991	15.515832685677847
1992	10.194437213400349
1993	7.280372194428764
1994	7.499376331292817
1995	9.375113269781435
1996	11.600776496061522
1997	12.313908592978361
1998	9.179037739223753
1999	9.104412844649175
2000	11.255302802552027
2001	13.15440417901649
2002	12.876816130201298
2003	16.372618207480592
2004	14.704268095822304
2005	13.159241397490968
2006	14.048100696785795
2007	12.85680285600952
2008	10.771901005749353
2009	7.592436214488208
2010	9.868401683987399
2011	11.778969681397738
2012	9.087469072915152
2013	9.456235476374903
2014	7.970332381199688
2015	8.226608163463563