Year | Value | 2019 | 0.091 | 2018 | 0.083 | 2017 | 0.082 | 2016 | 0.062 | 2015 | 0.064 | 2014 | 0.047 | 2013 | 0.046 | 2012 | 0.046 | 2011 | 0.037 | 2010 | 0.044 | 2009 | 0.043 | 2008 | 0.031 | 2004 | 0.053 | 2001 | 0.04 | 1997 | 0.038 | 1996 | 0.035 | 1995 | 0.034 | 1989 | 0.029 | 1986 | 0.004 | 1983 | 0.018 | 1981 | 0.018 | 1980 | 0.018 | 1970 | 0.01 | 1965 | 0.014 | 1960 | 0.011 |
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