Year	% of total
1960	0.025731140956445336
1961	0.025528470471031413
1962	0.036462292427585266
1963	0.047976485449157065
1964	0.08438818565400844
1965	0.2709229047647093
1966	0.2667710037703635
1967	0.46911456173683785
1968	1.0330952985101678
1969	1.949956557486982
1970	3.540866518428677
1971	5.6375853822294
1972	8.126936735201648
1973	8.642002744551176
1974	11.045403537521599
1975	11.83488746469034
1976	12.372263891014848
1977	13.075747653350797
1978	13.48419470571124
1979	13.841946049219853
1980	15.27656449795536
1981	15.990898212989663
1982	17.025998943730237
1983	17.81958676297665
1984	18.83326059396887
1985	19.29601634855968
1986	19.050719825668736
1987	18.81500480923373
1988	18.572705008131543
1989	18.01471283496284
1990	19.42023280461298
1991	20.43165936108286
1992	21.0047786538392
1993	24.482170687486125
1994	25.760573974112333
1995	28.44689465753686
1996	31.942339808320785
1997	33.420928340321254
1998	34.627073881492485
1999	36.91710621027644
2000	37.76016675469705
2001	36.448422898912725
2002	37.08495200196141
2003	36.28576593860685
2004	37.05947337365393
2005	36.21145541990381
2006	34.27741858060705
2007	35.47598665809963
2008	37.7998759744173
2009	38.458876633986925
2010	40.32033147221819
2011	36.25166396651815
2012	32.55220112186349
2013	33.25520438793979
2014	33.0918353621791
2015	35.297977620700856
2016	41.9543358230621