Year	% of total
1971	1.19872497215218
1972	1.2863449857261977
1973	1.1897358670562552
1974	2.4041647214817887
1975	2.8553726832972486
1976	3.6320412788075824
1977	3.1826341115382712
1978	5.955859262837501
1979	6.932815832028886
1980	8.022990293141389
1981	8.399877680042533
1982	9.628117620178397
1983	10.74291090602262
1984	12.16240442962456
1985	13.810001958211386
1986	14.354075209172063
1987	15.437245685285205
1988	13.771708346722589
1989	13.324472900276325
1990	13.725298686528737
1991	13.735096009325186
1992	13.43009094969342
1993	13.829241712909893
1994	14.064560391774162
1995	14.23399096578684
1996	14.21297460861248
1997	14.186148225217753
1998	14.70560442249993
1999	14.0761936064625
2000	13.4956763179438
2001	12.840143186014691
2002	11.869943935097202
2003	10.43989753599562
2004	10.641455158287021
2005	10.672679667732472
2006	9.895930246209257
2007	8.431572409796564
2008	8.34525513093292
2009	8.338063186328657
2010	7.72683569506715
2011	5.032888023436391
2012	3.8149759435209916
2013	3.557551170958363
2014	3.784423601095025
2015	1.945801147416746