Year	% of total
1960	-0.018782870022539443
1961	-0.017985611510791366
1962	-0.01518141794443601
1963	-0.012599218848431397
1964	-0.01301913813305559
1965	0
1966	-0.01163061177017911
1967	0.01126126126126126
1968	0.06106870229007633
1969	0.06737895851381268
1970	0.20930020930020926
1971	0.48085329603077465
1972	0.5973205904940695
1973	0.7530120481927711
1974	1.7768741159830268
1975	3.029450384543238
1976	3.0615942028985503
1977	3.4451981435201713
1978	3.6827933640232775
1979	4.355016538037487
1980	4.8937132519222075
1981	5.510993677455883
1982	6.176794473921314
1983	6.204813764070651
1984	7.0766638584667225
1985	7.292146211214439
1986	7.031385469048032
1987	7.916552792201877
1988	7.881462799495587
1989	8.845117532286537
1990	8.623754904223402
1991	9.185566017079044
1992	9.65295623632385
1993	10.650757192174913
1994	10.710842920873445
1995	11.573335635359117
1996	12.364980686207682
1997	12.291955555555555
1998	12.223333333333333
1999	12.582923871547273
2000	12.751864561885151
2001	12.84586802480071
2002	13.070578379619002
2003	13.420042372881355
2004	13.71075750883392
2005	13.900209378407851
2006	13.626275285839927
2007	13.862843362425355
2008	14.297711298932384
2009	14.132267002518892
2010	15.248750276487502
2011	14.840711337703327
2012	15.783555450906523
2013	16.23499310027599
2014	15.39530833123584
2015	16.73309505508583
2016	17.3305326937642