Year	% of total
1971	38.107416879795394
1972	28.132387706855795
1973	26.13168724279835
1974	22.928709055876688
1975	25.925925925925924
1976	29.411764705882355
1977	31.831395348837212
1978	14.756258234519104
1979	12.925969447708576
1980	13.686534216335541
1981	16.902834008097166
1982	19.197707736389685
1983	26.848591549295776
1984	26.800670016750416
1985	6.451612903225806
1986	3.054989816700611
1987	2.7824151363383414
1988	2.7635619242579326
1989	2.3984336759667158
1990	1.7248814144027595
1991	1.4492753623188406
1992	6.444728979940248
1993	11.865729898516785
1994	22.184154175588866
1995	38.67302052785924
1996	33.518095859145745
1997	33.5140306122449
1998	43.689604685212295
1999	37.85277858597615
2000	38.08871851040526
2001	50.74665293511843
2002	60.034096444227956
2003	60.82451499118166
2004	70.03297609233306
2005	67.05336426914154
2006	63.07178631051753
2007	62.399368587213885
2008	62.00946709421286
2009	55.24528301886793
2010	52.191235059760956
2011	53.22095910100614
2012	50.697674418604656
2013	53.24498389893485
2014	56.17068922617566
2015	57.7244841048522