Year	% of total
1960	11.174267627321635
1961	11.836688446576273
1962	12.54867256637168
1963	10.602744484974814
1964	14.376474579407548
1965	15.096781699460465
1966	16.372300861179063
1967	15.998907302859225
1968	18.307238813182565
1969	18.98030514499755
1970	18.35402259353121
1971	19.149931882234267
1972	20.084281824566805
1973	21.470370619492837
1974	21.43381039249243
1975	21.650569703237245
1976	24.79452683777951
1977	25
1978	25.159589475911687
1979	25.48588587592179
1980	25.29887235151525
1981	25.60824812600735
1982	26.618635077793495
1983	27.924629878869446
1984	28.508284436632458
1985	29.692794217302914
1986	28.607899763713235
1987	27.638357561846465
1988	27.914961364349068
1989	29.903590425531913
1990	29.91467765794999
1991	30.730761872472335
1992	31.389003521126764
1993	33.57454812151036
1994	33.92990314935509
1995	34.19487697441602
1996	34.83159124276708
1997	33.96494284579859
1998	32.05121928671214
1999	32.90924021488872
2000	33.024361165048546
2001	32.47451335463763
2002	31.969970502597672
2003	33.483496956139064
2004	33.262710283852954
2005	33.60288724839537
2006	33.60529968395956
2007	31.708436225516795
2008	32.89169701926572
2009	34.48937423195084
2010	33.68995850699961
2011	34.898495946834146
2012	34.81016065358043
2013	35.69186968634852
2014	36.04080825160636
2015	35.781467788117396
2016	39.425179479726786