Year	% of total
1960	22.840103159252095
1961	25.11756569847856
1962	27.577830100534445
1963	30.276978541962773
1964	34.341504828610844
1965	38.42248035055992
1966	41.70791216451725
1967	43.4761839770711
1968	46.209520274659
1969	48.21571593841773
1970	52.04775666287183
1971	54.97118373012281
1972	54.668011995851906
1973	53.06435003036625
1974	47.20271186440678
1975	50.35889119139863
1976	50.02538500592316
1977	50.68374087379765
1978	50.696393867415246
1979	48.431044401443444
1980	47.277556440903055
1981	44.841962094556635
1982	45.24752784103316
1983	45.07306512718744
1984	41.45883335072524
1985	42.29203229203229
1986	49.01261852142297
1987	47.21194879089616
1988	48.901962217268974
1989	44.1426377751237
1990	41.74898453938341
1991	44.917210424710426
1992	47.70397133446097
1993	47.110509490509486
1994	46.35611401218451
1995	45.86230514096186
1996	47.534389284219344
1997	48.29914351851852
1998	47.498106523741725
1999	46.968457276426285
2000	44.20848652796726
2001	45.73369359472706
2002	45.03281100586378
2003	47.407483982683985
2004	46.79750657779337
2005	47.31527348341018
2006	46.623044638748276
2007	46.39934793001243
2008	47.5375984288787
2009	50.661773853717264
2010	51.63833098525406
2011	52.94646123260437
2012	49.83042122999158
2013	50.59632543214988
2014	55.08227706299911
2015	55.34011449579832
2016	53.48485899067006