Year	% of total
1960	2.7085856575392353
1961	3.6981042466458227
1962	4.572706543989626
1963	6.28391868894636
1964	7.745970798992394
1965	9.97637726384555
1966	12.317540453807101
1967	11.83605163316035
1968	11.945622115256182
1969	12.974400306359179
1970	12.208400400296659
1971	11.66023425587244
1972	12.211425316799708
1973	11.976161473693208
1974	8.272160957387156
1975	8.248951194726008
1976	8.53987561191487
1977	7.220228469228007
1978	7.411814078495627
1979	6.281585976949054
1980	5.734228245486126
1981	4.462550535878068
1982	3.785656759429962
1983	2.680522640045301
1984	1.82360854713423
1985	1.8432073151990163
1986	2.614538158305753
1987	2.6035549807999367
1988	2.1556947518684577
1989	1.872453565412085
1990	1.8984753035697983
1991	2.75089301377686
1992	2.476614849570523
1993	1.9313399185051494
1994	1.6705857712702659
1995	1.6859541979002053
1996	1.4465462482590055
1997	1.252894558685866
1998	1.1542883005204796
1999	1.0578323937416862
2000	0.8360809557008141
2001	0.8176859384827956
2002	0.7426703828824959
2003	1.711886786513652
2004	1.76319945017632
2005	1.9481974667099708
2006	1.7313807425576706
2007	1.5792306004926908
2008	1.525584034805637
2009	1.7062000183061397
2010	1.3950266764339283
2011	1.1794581277543197
2012	1.222828265337861
2013	1.137223613426127
2014	0.9098977711604693
2015	0.9686926160005117