Year	% of total
1960	63.976816763263486
1961	63.00927793465107
1962	64.40677966101694
1963	63.49670811997075
1964	63.73918829008649
1965	65.25450521656654
1966	65.37747524752476
1967	69.76950354609929
1968	72.97068771138669
1969	74.32873274780427
1970	72.62677241047825
1971	78.25212337952615
1972	83.49320543565148
1973	81.02658111824013
1974	83.20056647194194
1975	84.27197802197801
1976	85.87080948487326
1977	85.04356243949663
1978	81.34472750725573
1979	83.03545268092589
1980	83.35371653757304
1981	84.32323232323232
1982	85.69816996741038
1983	84.65370595382747
1984	85.02397173858188
1985	79.76986887877977
1986	73.18274660579118
1987	68.68604651162791
1988	67.01191669450941
1989	69.53194518597616
1990	68.9917433649866
1991	68.29862520458265
1992	71.12113961941417
1993	67.94240663900415
1994	65.57185200845666
1995	67.62500690471494
1996	68.50985227739022
1997	68.53754761437267
1998	71.40097482014389
1999	65.13478540427585
2000	62.52217158611742
2001	65.7228201368524
2002	64.76634049687549
2003	63.54234798413747
2004	61.618348623853215
2005	60.648046433480985
2006	57.70747890818859
2007	58.13567006802721
2008	58.282332864180155
2009	55.26553285968028
2010	57.45254613270514
2011	53.12627832364147
2012	49.430734135213605
2013	52.146063144329894
2014	52.88527759634226
2015	49.70495285857573
2016	53.33544708777686