Year	% of total
1960	5.6351480420248325
1961	6.675102815564695
1962	10.380952380952381
1963	15.086483023702755
1964	16.895113230035758
1965	20.3125
1966	24.39255285579047
1967	27.630729502905105
1968	28.212791392707715
1969	28.932740411339637
1970	29.714590557481994
1971	31.861111111111107
1972	32.58152173913044
1973	34.54968944099379
1974	30
1975	32.693498452012385
1976	35.18117064106534
1977	37.88590604026845
1978	35.28319405756732
1979	31.185722928009678
1980	27.003658131027603
1981	30.493971217425127
1982	32.20198675496689
1983	32.950022114108805
1984	29.938398357289525
1985	31.56
1986	35.12413512413512
1987	41.53976311336717
1988	41.190965092402465
1989	42.255125284738035
1990	38.937579505300356
1991	44.10983870967742
1992	46.909441535776615
1993	46.12815766923736
1994	48.746743542435425
1995	54.58253456221198
1996	55.50732876712329
1997	60.21506650544135
1998	67.63899868247695
1999	67.75877987421384
2000	68.21132867132867
2001	67.92375273522975
2002	63.98616869918698
2003	66.58500000000001
2004	66.62135273972602
2005	68.18040201005024
2006	65.46875638841567
2007	67.54653500897666
2008	68.62338768115941
2009	67.4854206500956
2010	66.94098553345388
2011	70.42116193961574
2012	69.84108512628625
2013	72.40066995073892
2014	72.58
2015	74.06295728368018
2016	74.62303611738147