Year | Value | 2022 | 24.63055097478 | 2021 | 20.292334368326 | 2020 | 16.30696649764 | 2019 | 20.258626658087 | 2018 | 22.140894480847 | 2017 | 17.358321189065 | 2016 | 16.976093238103 | 2015 | 16.400559409388 | 2014 | 23.445575523214 | 2013 | 26.280052017443 | 2012 | 27.698275104461 | 2011 | 30.403588523709 | 2010 | 26.630448355137 | 2009 | 27.228455914049 | 2008 | 29.961488725964 | 2007 | 41.031679970482 | 2006 | 45.95742472023 | 2005 | 39.557573643808 | 2004 | 33.657794660217 | 2003 | 25.038073118947 | 2002 | 16.282913045996 | 2001 | 17.91789010489 | 2000 | 17.423610400329 | 1999 | 33.437759640242 | 1998 | 30.866900481529 | 1997 | 37.163973725802 | 1996 | 33.032632858657 | 1995 | 38.79343834413 | 1994 | 40.56227061423 | 1993 | 41.801938376105 | 1992 | 36.496968710217 | 1991 | 25.482098783947 | 1990 | 23.384450692371 | 1989 | 14.913955403034 | 1988 | 7.9471759826692 | 1987 | 8.4889431001325 | 1986 | 13.596182583843 | 1985 | 19.252575848226 | 1984 | 20.031822985145 | 1983 | 21.047078661879 | 1982 | 31.2268530121 | 1981 | 22.316396152298 |
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