Year	% of total
1960	16.063178252927905
1961	23.460101542293323
1962	29.827548570181182
1963	18.372784492412247
1964	30.075187969924812
1965	37.94288236035809
1966	27.657315746171605
1967	44.21381789530704
1968	46.582698478531356
1969	39.59566453993389
1970	48.95121041507557
1971	44.15685637736462
1972	40.689096664948835
1973	53.062384351044145
1974	52.742394725011245
1975	58.92469974908037
1976	67.87046893383383
1977	49.874310867524734
1978	50.94416408920722
1979	49.0482603172784
1980	67.8666251625071
1981	70.96803520128005
1982	68.64571035892376
1983	66.83249839657474
1984	53.33005943813185
1985	52.28193636211659
1986	49.70677231181957
1987	47.80251270681568
1988	37.66596432488599
1989	48.28464673913043
1990	46.80766636244593
1991	46.0306690188628
1992	51.80599872367581
1993	47.68944730730383
1994	47.4518651104399
1995	51.60269571728786
1996	43.46725117526606
1997	50.88793372350605
1998	50.09359228923637
1999	57.78310022007705
2000	55.95393828563151
2001	51.36891966687691
2002	59.78567587957502
2003	54.146117763191135
2004	57.697757471480415
2005	63.63834234483235
2006	61.70098314511709
2007	62.08342858278751
2008	60.7030079298214
2009	56.164238065707565
2010	46.170555108608205
2011	49.848902182600256
2012	49.200182348898764
2013	40.01883138801542
2014	38.80319622911885
2015	44.067143762239375