Year	% of total
1960	49.99384312276813
1961	45.59741160157152
1962	43.06852035749751
1963	39.6270606251689
1964	34.54746136865342
1965	30.973451327433633
1966	28.06876371616679
1967	25.629530000747213
1968	23.146747352496217
1969	19.3715661460584
1970	15.081192795984649
1971	10.063620589936379
1972	8.939440516446357
1973	15.31369879965351
1974	14.866844207723037
1975	19.433304845177833
1976	20.36709555460699
1977	22.216293134115972
1978	21.07757844843103
1979	25.87892898719441
1980	36.500030371135274
1981	34.95716207604617
1982	41.125452434610395
1983	39.823138200686984
1984	42.04037490987743
1985	46.6548650958369
1986	45.894291228288616
1987	47.1213073538655
1988	47.15863721054032
1989	42.04750450992183
1990	44.18284370199693
1991	50.331372549019605
1992	45.06402736362042
1993	46.65853938269523
1994	46.76745212850134
1995	39.711553738317754
1996	47.17572987721692
1997	38.41372410546139
1998	36.84187144291931
1999	31.24932935393258
2000	28.85040599506735
2001	29.662863509749304
2002	29.86315672471286
2003	36.23742500842602
2004	30.49822601595843
2005	28.244726477024066
2006	36.02744030235355
2007	32.86565917602996
2008	30.31932960893855
2009	31.70817916057632
2010	29.98750518887505
2011	28.474778370851705
2012	24.501049463491235
2013	28.60773636818409
2014	25.543895413870242
2015	19.49185119047619
2016	20.31464104013567