Year | Value | 2022 | 33.438805284806 | 2021 | 32.712057560298 | 2020 | 31.119694485089 | 2019 | 30.399196450652 | 2018 | 28.611484918546 | 2017 | 28.537003833235 | 2016 | 27.099309264966 | 2015 | 27.498334199279 | 2014 | 27.564801693041 | 2013 | 27.336827567999 | 2012 | 27.693965977193 | 2011 | 29.032994302704 | 2010 | 29.140820796584 | 2009 | 27.336164119415 | 2008 | 32.039602629325 | 2007 | 32.555039403837 | 2006 | 31.135863607229 | 2005 | 28.38206149683 | 2004 | 27.793203899059 | 2003 | 27.787784714916 | 2002 | 26.435123335091 | 2001 | 27.219578517535 | 2000 | 26.814579513341 | 1999 | 25.661040703448 | 1998 | 24.228742002363 | 1997 | 23.104671241283 | 1996 | 22.573651304073 | 1995 | 22.58677545856 | 1994 | 19.65033684067 | 1993 | 16.05423516426 | 1992 | 17.972757067463 | 1991 | 20.907943582919 | 1990 | 24.028053116331 | 1989 | 25.145652375694 | 1988 | 24.45788319756 | 1987 | 23.765912246472 | 1986 | 23.583886228192 | 1985 | 23.127250509407 | 1984 | 23.294352345228 | 1983 | 20.938493129901 | 1982 | 18.953163118469 | 1981 | 20.133705199476 | 1980 | 21.790605572321 | 1979 | 21.075960143371 | 1978 | 20.439506238737 | 1977 | 20.954939802465 | 1976 | 24.256391162283 | 1975 | 26.545208048805 | 1974 | 25.81099459732 | 1973 | 26.965933306136 | 1972 | 26.352262337179 | 1971 | 26.880494999066 | 1970 | 27.586078070651 |
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