| Year | Value | | 2022 | 0.51559254436947 | | 2021 | 0.91961473898276 | | 2020 | 0.19436644370107 | | 2019 | 1.671348097374 | | 2018 | 2.8750028594538 | | 2017 | 0.54718566522852 | | 2016 | 0.53575873239208 | | 2015 | 0.52000388065714 | | 2014 | 0.49314930761236 | | 2013 | 0.46319412619233 | | 2012 | 0.035479198004734 | | 2011 | 0.49619379069059 | | 2010 | 0.4437069960101 | | 2009 | 0.38421525030741 | | 2008 | 0.31390050472379 | | 2007 | 0.24371450743819 | | 2006 | 0.17680278847466 | | 2005 | 0.094070723117922 | | 2004 | 0.018146123682747 | | 2003 | 0.03142906951772 | | 2002 | 0.067625708765911 | | 2001 | 0.099811709167283 | | 2000 | 0.13671136853235 | | 1999 | 0.17389460192429 | | 1998 | 0.19657287063803 | | 1997 | 0.21739398347655 | | 1996 | 0.25005659894665 | | 1995 | 0.28549846701167 | | 1994 | 0.31495247299702 | | 1993 | 0.29366313666619 | | 1992 | 0.1211475044987 | | 1991 | 0.405040212764 | | 1990 | 0.77079713603801 | | 1989 | 0.73484447824507 | | 1988 | 0.69060213139449 | | 1987 | 0.62680744622368 | | 1986 | 0.54023706850006 | | 1985 | 0.43081972622263 | | 1984 | 0.30430182407039 | | 1983 | 0.16264330345523 | | 1982 | 0.0060282494046106 | | 1981 | 0.19385548564391 | | 1980 | 0.47583008876178 | | 1979 | 0.76120311222751 | | 1978 | 0.94524382754765 | | 1977 | 1.0330595374961 | | 1976 | 1.0623502749351 | | 1975 | 1.0637257810342 | | 1974 | 1.0679007920283 | | 1973 | 1.084275692466 | | 1972 | 1.1268329090637 | | 1971 | 1.2180552451963 | | 1970 | 1.3334672814911 | | 1969 | 1.4520383125991 | | 1968 | 1.5905389932782 | | 1967 | 1.7669077810835 | | 1966 | 1.9847649651838 | | 1965 | 2.2159822738466 | | 1964 | 2.427824433086 | | 1963 | 2.5900319791852 | | 1962 | 2.7210647922429 | | 1961 | 2.862023023693 |
|