Year	% of total
1960	19.42358924679099
1961	19.944394008170676
1962	22.88236821604778
1963	30.122950819672127
1964	39.59521218715996
1965	46.2015193922431
1966	46.596576841652016
1967	38.84083044982699
1968	36.990987239358695
1969	39.0453370665518
1970	32.60316217142298
1971	26.22260823089257
1972	20.526326411172327
1973	12.328272559712696
1974	7.162031372692244
1975	7.936156880091414
1976	7.874503328345115
1977	7.526678790790241
1978	16.908565491265666
1979	33.86231074708365
1980	38.42082523223158
1981	39.86230153154419
1982	24.07149489322191
1983	9.466890192791283
1984	5.358565102424416
1985	5.175782801404356
1986	5.146073438756366
1987	5.34792966865929
1988	5.453161138325839
1989	4.52703627652293
1990	4.257447754557582
1991	4.441815444181545
1992	4.083772344253595
1993	3.9217719255044776
1994	4.170683761753916
1995	3.466926213855385
1996	3.3059012209826393
1997	3.262716271973926
1998	3.3068100751797176
1999	3.2068726937269374
2000	2.946525197755241
2001	2.825021620063419
2002	2.4619455933986933
2003	2.5749344130223717
2004	2.4018416424605293
2005	2.2637883928303357
2006	2.1197373346959014
2007	2.1100175914039845
2008	1.9200014876524845
2009	1.3079311467046644
2010	1.0505575584807578
2011	1.233733755692637
2012	1.0251892582625026
2013	1.1824722811983959
2014	1.8430060531048755
2015	1.3000817661488144