Year	% of total
1971	13.442482126264037
1972	12.409403034330527
1973	13.094208080979842
1974	11.787719158772045
1975	10.901800577238596
1976	9.83298327525011
1977	11.332406480322001
1978	8.5234463022668
1979	9.022898161528978
1980	11.073828050072759
1981	9.058182925145207
1982	9.097829754099223
1983	8.279946878330708
1984	7.316932442450341
1985	7.296229421269944
1986	7.299497265067366
1987	7.379497643490232
1988	7.512069651014663
1989	7.465716398199533
1990	5.462147270446114
1991	4.924536038679404
1992	5.505030538366441
1993	6.146608653763056
1994	5.37078623186992
1995	5.672039511686073
1996	5.552479913471011
1997	6.487632185065843
1998	5.32125104225232
1999	5.595292912884301
2000	6.737874854813622
2001	6.559086197193699
2002	6.0018864091817985
2003	6.846046435594223
2004	6.705884108935571
2005	6.010092174883126
2006	6.258186511363116
2007	7.342438644111445
2008	7.008780099016036
2009	7.651357912172423
2010	7.960892564691783
2011	9.03128751876451
2012	8.269956258140546
2013	9.081396974178869
2014	12.619953471863543