Year	% of total
1960	0.2771911298838437
1961	0.3181733108740408
1962	0.2108862923909946
1963	0.12226238571124814
1964	0.1216485815775388
1965	0.13530537022348715
1966	0.15895443306252208
1967	1.426702123169136
1968	0.8012093726379441
1969	4.940853763072176
1970	13.285063722438817
1971	18.575683725968048
1972	20.766324878575286
1973	23.703065369937214
1974	25.71961998392967
1975	21.968249301778627
1976	19.56157290495087
1977	16.040453178006786
1978	13.259755928716945
1979	14.01406415566901
1980	11.24107664199205
1981	9.800003995924158
1982	4.720076833806875
1983	7.1217875802502455
1984	5.202086049543676
1985	4.235766721768961
1986	1.688620468232068
1987	3.3596996486274002
1988	3.9494274957004074
1989	8.035647532036425
1990	7.689352984692426
1991	8.732054055572725
1992	9.337627783223638
1993	9.721984358052179
1994	11.599220644510169
1995	13.84868600032646
1996	14.653038409326838
1997	14.817431063048254
1998	18.319829424307034
1999	23.068157282345318
2000	19.30218791151704
2001	20.071739296344347
2002	22.075884307935606
2003	25.860150070008736
2004	25.460860905954736
2005	26.65881062665531
2006	27.294067434912506
2007	29.00329037565122
2008	29.486857375303586
2009	32.63701757120905
2010	33.485021261176776
2011	28.57752713056373
2012	28.847968047438773
2013	25.4661408889538
2014	27.017426085983608
2015	32.806119514579855