| Year | Value | | 2022 | 0.44385191914853 | | 2021 | 0.45995241580764 | | 2020 | 0.29419461775007 | | 2019 | 0.14046497787817 | | 2018 | 0.12688006808879 | | 2017 | 0.081874296046114 | | 2016 | 0.051137415213363 | | 2015 | 0.10612499374675 | | 2014 | 0.13269422214704 | | 2013 | 0.14427188338708 | | 2012 | 0.15971067584435 | | 2011 | 0.18522648641085 | | 2010 | 0.017960541519564 | | 2009 | 0.01249463122941 | | 2008 | 0.048425394597897 | | 2007 | 0.11490884772621 | | 2006 | 0.063373589418133 | | 2005 | 0.0093920965576634 | | 2004 | 0.033662258272545 | | 2003 | 0.21398094877968 | | 2002 | 0.23252718710568 | | 2001 | 0.24095258752107 | | 2000 | 0.16727557811319 | | 1999 | 0.18258637414011 | | 1998 | 0.27172961023119 | | 1997 | 0.23827121759148 | | 1996 | 0.2268847324609 | | 1995 | 0.23459017341292 | | 1994 | 0.27919236397367 | | 1993 | 0.32416759914373 | | 1992 | 0.37119238719853 | | 1991 | 0.39281983248186 | | 1990 | 0.33178288536374 | | 1989 | 0.39976116450429 | | 1988 | 0.41611034219518 | | 1987 | 0.48203549697478 | | 1986 | 0.53235736636232 | | 1985 | 0.6259359636246 | | 1984 | 0.6483167367329 | | 1983 | 0.69558330306927 | | 1982 | 0.69365614942474 | | 1981 | 0.72846083601409 | | 1980 | 0.78815347588554 | | 1979 | 0.84661450291584 | | 1978 | 0.91003097602261 | | 1977 | 0.96803272624558 | | 1976 | 1.071559810223 | | 1975 | 1.2727075526325 | | 1974 | 1.3295820188062 | | 1973 | 1.407188740543 | | 1972 | 1.4007791812815 | | 1971 | 2.1942535066501 | | 1970 | 1.151640472218 | | 1969 | 1.1888148668928 | | 1968 | 1.1269968454954 | | 1967 | 1.0345787443693 | | 1966 | 0.91361031403398 | | 1965 | 1.0767084593203 | | 1964 | 1.0404496280407 | | 1963 | 1.0134602261801 | | 1962 | 0.92916620826076 | | 1961 | 0.89603367679599 |
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