Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0.8239115720064385
1971	0.8458391011126084
1972	0.8144419612525695
1973	0.7778775056631192
1974	0.26781850815361413
1975	0.28741173098470435
1976	0.29685138210301765
1977	0.2865840634850594
1978	0.28238245969632164
1979	0.2827365994187004
1980	0.611570956812626
1981	0.6272755843561659
1982	0.56503933912828
1983	0.5178163209664226
1984	0.5256014609534748
1985	0.5440295066851083
1986	0.49826278762698517
1987	0.43489981469158306
1988	0.43428274804472233
1989	0.45568957134681387
1990	0.30439149091573087
1991	0.38967873899362854
1992	0.4380968085265856
1993	0.5056585139917357
1994	0.6669776563437134
1995	0.7792588032596741
1996	0.8342246377732704
1997	1.041037497422497
1998	1.3914460285132384
1999	1.641495262829272
2000	2.4013083749626514
2001	2.6056650271702706
2002	3.669190348378051
2003	4.617107602182229
2004	5.979005244597901
2005	6.9611886976291
2006	8.159852828685763
2007	10.597273314048634
2008	11.476717424887292
2009	12.852774566669945
2010	13.383063377078535
2011	17.473173173832564
2012	19.51250404830388
2013	20.439058685983774
2014	22.98074727705977
2015	26.271087279064286