Year	% of total
1971	46.34365186182144
1972	29.14614121510673
1973	18.246614397719174
1974	16.6883963494133
1975	24.958677685950413
1976	23.06965761511216
1977	24.02933563416739
1978	19.37956204379562
1979	12.319178721418572
1980	12.242032851326687
1981	12.03635470400393
1982	12.611749680715198
1983	11.724407907614015
1984	10.516902164192452
1985	9.336809516050188
1986	9.22887296818427
1987	8.646439239113347
1988	7.926392667907776
1989	7.347950926651005
1990	5.42722305017387
1991	4.318247333525512
1992	4.232746363338072
1993	3.229628103430514
1994	3.767037167429462
1995	3.3223433933553133
1996	3.602207804783577
1997	3.847048425361679
1998	3.4476829163442524
1999	2.734580118754292
2000	3.0418699826853453
2001	2.910798122065728
2002	2.159288194444444
2003	2.3232220756822564
2004	2.1984
2005	2.114108801415303
2006	2.129109180718787
2007	2.134638133132595
2008	1.9683865195347447
2009	1.5765824264304822
2010	2.1078409935715223
2011	2.084960174918007
2012	1.8450441660713974
2013	1.506094506595425
2014	0.9931197658852465
2015	1.319805808308381