Year | Value | 2021 | 18.219302507023 | 2020 | 17.604648515284 | 2019 | 17.715919830068 | 2018 | 17.608744834326 | 2017 | 17.68617693169 | 2016 | 17.692264253813 | 2015 | 17.647295017746 | 2014 | 17.279792564244 | 2013 | 17.27686075985 | 2012 | 17.125750770518 | 2011 | 17.118146324683 | 2010 | 16.916312758598 | 2009 | 16.730732100171 | 2008 | 18.165702227466 | 2007 | 18.234899034094 | 2006 | 17.79200893185 | 2005 | 17.510113204147 | 2004 | 17.308923769277 | 2003 | 17.712152646448 | 2002 | 17.435514032393 | 2001 | 17.293841540997 | 2000 | 18.060989555464 | 1999 | 18.585745762464 | 1998 | 19.349993411521 | 1997 | 19.483383076082 | 1996 | 19.536185541966 | 1995 | 20.281303395084 | 1994 | 20.885785399938 |
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