Year	% of total
1971	6.145584725536993
1972	6.382978723404255
1973	9.373571101966164
1974	8.409986859395532
1975	12.354025814382299
1976	15.953079178885632
1977	17.443868739205527
1978	18.68377021751255
1979	16.518650088809945
1980	16.82577565632458
1981	16.5083135391924
1982	15.17766497461929
1983	18.334179786693753
1984	3.404255319148936
1985	3.056234718826406
1986	2.9036004645760745
1987	3.8274932614555257
1988	4.860731840524304
1989	5.158069883527454
1990	3.986981285598047
1991	2.2138483278379653
1992	2.3005751437859465
1993	3.350039567396465
1994	3.643979057591623
1995	3.516898267284269
1996	4.190129181848294
1997	4.172661870503598
1998	3.1635802469135803
1999	3.0715690724769256
2000	3.1032394792612776
2001	2.5540865384615383
2002	0.8941447937698297
2003	0.8816120906801008
2004	1.4271858112789246
2005	1.6437617892751282
2006	1.7262143717382576
2007	2.3015343562374917
2008	2.408500590318772
2009	4.183719872669395
2010	4.166666666666666
2011	5.245075584058635
2012	7.132094424912104
2013	6.9371399949912345
2014	6.498545101842872
2015	7.132459970887918