Year	% of total
1960	5.4818744473916885
1961	21.44313086017122
1962	30.570902394106813
1963	37.52577319587629
1964	43.275199527047
1965	45.46193443511243
1966	50.56179775280899
1967	53.84615384615385
1968	47.00801974090068
1969	49.686609686609685
1970	53.79036435848731
1971	62.86484771573604
1972	64.13122368994048
1973	66.31736526946108
1974	65.61394312671996
1975	67.78353942294908
1976	65.50312951372172
1977	66.72209289435762
1978	71.63591125855277
1979	67.78195488721805
1980	60.42968010600038
1981	44.116250356159185
1982	28.442545109211775
1983	22.19028189910979
1984	20.07831968672125
1985	20.645600885784855
1986	43.698708052327945
1987	21.316018687148627
1988	7.5222954633578905
1989	5.290379784247081
1990	10.03584229390681
1991	16.289350301406564
1992	15.665399239543726
1993	14.496253637996162
1994	16.852864273829333
1995	15.22381276982504
1996	14.201902748414378
1997	17.598659149779063
1998	23.22540473225405
1999	28.34367103147255
2000	19.59194018502091
2001	21.122929522572264
2002	15.01026446081391
2003	9.870882104501026
2004	12.7344834423954
2005	13.033637711699056
2006	10.451394010916063
2007	6.891227062161094
2008	5.714190183228567
2009	3.283496673581801
2010	2.140119250425894
2011	0.8614342512148432
2012	0.8695331785859033
2013	0.7390029325513197
2014	1.0035647861128332
2015	1.44845012278017