Year	% of total
1960	50.649350649350644
1961	51.47615442846328
1962	44.44444444444444
1963	43.1143339376133
1964	38.33974466187211
1965	39.66730979819575
1966	36.93274377472655
1967	28.123076923076923
1968	27.008641294355577
1969	23.954856143697345
1970	21.25140924464487
1971	21.990075737790544
1972	19.990603711533943
1973	14.348918212154615
1974	18.09285389167046
1975	17.627962616190352
1976	16.48743964401805
1977	13.783905805191443
1978	12.558357178201845
1979	13.794205077390917
1980	15.42134836366939
1981	15.095230545464572
1982	14.101265910276926
1983	13.71648719384367
1984	11.131732050068468
1985	12.425986706470288
1986	12.042246805264162
1987	10.488898488242118
1988	12.068811110294266
1989	11.558867812797269
1990	9.958317909317099
1991	10.569399876350131
1992	8.8821032757107
1993	10.21059069777111
1994	6.7395783735859585
1995	8.016767068373513
1996	7.717156968089439
1997	8.410549507914817
1998	8.616397900540141
1999	7.900983479455364
2000	7.8337125904794815
2001	7.676528614331336
2002	7.3772676440498355
2003	8.559085274473164
2004	8.27935153368374
2005	6.771061614269966
2006	7.742862374964946
2007	6.41662223262629
2008	6.942679844632474
2009	7.197513218747455
2010	7.211174109523675
2011	7.743628262656216
2012	7.144019866897841
2013	7.370949399045836
2014	7.7588897225729285
2015	8.229092812861621