Year	% of total
1960	93.4224049331963
1961	93.40054995417047
1962	93.87938793879388
1963	94.53874538745387
1964	95.26255707762557
1965	93.38609383832674
1966	93.6606291706387
1967	94.55017301038063
1968	94.01120206807411
1969	94.30331023864511
1970	94.32446007031642
1971	89.90765171503958
1972	88.90481064483113
1973	87.7931323283082
1974	80.53897978825793
1975	78.16330379030738
1976	78.75997544505833
1977	78.91663963671748
1978	82.67318920624902
1979	81.79862884796344
1980	82.31827111984283
1981	84.83226266952177
1982	82.907520690896
1983	80.4828585224529
1984	74.10695413231875
1985	76.50273224043715
1986	70.00183418928833
1987	68.89168765743072
1988	71.31576688696249
1989	64.89744909211204
1990	68.23008542445275
1991	66.68114953418602
1992	66.2157862639756
1993	76.28122348644473
1994	71.68746883116883
1995	73.89083690987124
1996	72.68483648521577
1997	69.10059024390243
1998	57.98728454968944
1999	47.27878644249687
2000	46.451681052198936
2001	50.87286345349846
2002	45.45756619966259
2003	44.15393366247131
2004	43.618833428589575
2005	41.89912745628268
2006	36.47675411165161
2007	37.024355952001706
2008	35.41381593993935
2009	36.10481769970169
2010	37.36247752498619
2011	35.99176773937621
2012	37.05964580873672
2013	39.46253844054226
2014	38.686470131215465
2015	33.13466824338852
2016	38.37808038838348