Year	% of total
1971	66.76557863501483
1972	67.87330316742081
1973	70.20280811232449
1974	10.575635876840696
1975	13.57615894039735
1976	12.838801711840228
1977	12.005649717514125
1978	8.21917808219178
1979	13.26530612244898
1980	34.84848484848485
1981	75.43103448275862
1982	40.375586854460096
1983	43.4052757793765
1984	38.69346733668342
1985	31.818181818181817
1986	44.193548387096776
1987	46.42857142857143
1988	50.74183976261127
1989	39.83050847457627
1990	37.44493392070485
1991	31.422505307855626
1992	21.875
1993	12.244897959183673
1994	7.341772151898734
1995	7.107843137254902
1996	5.6722689075630255
1997	2.7860696517412937
1998	0.3933566433566434
1999	0.311284046692607
2000	0.45379537953795385
2001	0.37021455616323096
2002	0.29893014474512275
2003	0.339231686073164
2004	0.39269250469523653
2005	0.1580730146782085
2006	0.13571283164823233
2007	0.08086588703657627
2008	0.08593904938189992
2009	0.07663738725461298
2010	0.11400456018240729
2011	0.11883541295306002
2012	0.13846762495054726
2013	2.3430681436723733
2014	8.842425608656447
2015	13.58911263998393