Year	% of total
1971	96.2081784386617
1972	95.89675711449371
1973	98.80534082923401
1974	80.42704626334519
1975	62.330487192365645
1976	36.231884057971016
1977	14.929449248975876
1978	23.685127133402993
1979	29.3133294864397
1980	31.944444444444443
1981	40.591112056134385
1982	48.68442826410723
1983	57.58853288364249
1984	49.53488372093023
1985	52.20308938971891
1986	57.63031981868547
1987	57.69182626110903
1988	60.13105887247764
1989	54.40459110473458
1990	55.964171905951254
1991	44.25650710238936
1992	45.788887119885366
1993	48.93970564962811
1994	55.65142932419971
1995	53.170878459687124
1996	53.91200043618123
1997	53.76178761787618
1998	54.9269814263434
1999	54.4984442788904
2000	50.08525994368879
2001	45.8670260557053
2002	45.76089672651983
2003	41.77699522567975
2004	45.80228824391309
2005	50.50808644625734
2006	51.366574578226
2007	59.76398737125408
2008	61.6849084659825
2009	50.01616329546504
2010	39.44584491414043
2011	38.50453893932155
2012	38.297508409829526
2013	27.30809336648753
2014	22.513884273983006
2015	29.06437000167776