Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0
1974	1.8617439120188528
1975	3.078269169583201
1976	2.974828375286041
1977	3.424607520993063
1978	3.602458147912694
1979	3.4622393197003443
1980	3.0345001259128686
1981	2.726560831494269
1982	3.072601923567963
1983	3.086964191215382
1984	3.4626399375162715
1985	3.750738334317779
1986	4.2425909372206565
1987	5.196209374801246
1988	6.148548942449582
1989	8.110181311018131
1990	9.160778958944283
1991	9.58488481770361
1992	10.479146901300687
1993	10.638827160493827
1994	10.493751042883364
1995	11.591354965234444
1996	10.859758670289276
1997	10.979223028703396
1998	13.337455910598916
1999	13.52980888338347
2000	14.26203448275862
2001	13.93207889998363
2002	13.329290668348046
2003	13.075608701715241
2004	13.399070626477542
2005	14.896774251712946
2006	13.27933303491495
2007	13.130225806451612
2008	15.610314154606424
2009	14.727559985234404
2010	14.056931073084922
2011	13.964138243831641
2012	13.930295486743574
2013	13.034325562861127
2014	12.47224870017331
2015	11.963566090611863
2016	10.316696565302996