Year	% of total
1960	54.47314779040489
1961	48.46777827850383
1962	41.60566353810496
1963	47.70214610882289
1964	35.64881862650773
1965	44.172524925083394
1966	47.10367917121637
1967	38.81474256968328
1968	40.896038158278984
1969	38.50232761128892
1970	38.60048221656155
1971	31.342517436749674
1972	28.517356791140237
1973	26.129265566440925
1974	30.089859617762126
1975	32.43602059429879
1976	23.58433281355504
1977	36.26134473746733
1978	30.22308695748303
1979	27.61395439744832
1980	27.016649307444773
1981	26.189456880600805
1982	25.33756122786101
1983	23.508679268280297
1984	20.356544027174706
1985	18.07481448180433
1986	17.328807204089046
1987	18.72745336598998
1988	19.609360585497857
1989	11.557142644733776
1990	12.911344466309844
1991	12.754754080936733
1992	14.99007632426181
1993	13.817618927976765
1994	16.602436192695635
1995	14.885759597394957
1996	12.971168198601617
1997	12.727980438145616
1998	12.240717887656574
1999	13.911905716593411
2000	12.400034380698974
2001	13.619825192651197
2002	10.909271535140798
2003	10.497520943751068
2004	10.471945279668022
2005	9.012447261077362
2006	9.887747790780988
2007	10.217964318276152
2008	11.190888920925032
2009	10.740714917000055
2010	11.113710270519329
2011	8.050505504381038
2012	10.484644270997947
2013	12.468703054581873
2014	11.261935446865639
2015	9.661149896893312