Year	% of total
1960	3.5044754497007746
1961	3.726961273255562
1962	3.68144945025476
1963	3.5460366172063917
1964	3.170909090909091
1965	4.065813876075895
1966	4.073610198286231
1967	3.9348799252526567
1968	4.250898877026975
1969	3.0410799083019486
1970	3.0408759402802703
1971	3.144707955984907
1972	3.7358761939974077
1973	5.9978302805454655
1974	4.611748937445991
1975	5.596578605456908
1976	4.462477365703172
1977	3.8444100786892985
1978	2.9281991910343037
1979	3.0475341817270474
1980	2.462507835982833
1981	2.2204579214260103
1982	2.3314891738458083
1983	2.1562906112841134
1984	1.40042561955104
1985	1.4835217516364936
1986	1.4698662477213444
1987	1.2411133143105868
1988	1.8646285965071823
1989	2.970148357258694
1990	2.0027342072562293
1991	1.6957052753308512
1992	2.5221083303381455
1993	2.875119569568347
1994	2.7780727154279585
1995	3.7838947866536903
1996	3.2056328096500617
1997	3.6267433751743376
1998	4.609818587765668
1999	4.734819369715603
2000	5.52711708795963
2001	6.1007494319915905
2002	5.628304039869718
2003	5.6060467277988675
2004	5.727622048294199
2005	6.401686316725865
2006	7.310731024009636
2007	6.731667120047215
2008	6.830087391947027
2009	7.389546375349589
2010	8.612814975755809
2011	9.693834253726887
2012	10.2203562077182
2013	9.802854587407648
2014	9.603512490718785
2015	10.015952530041448