Year | Value | 2022 | 10.591788414775 | 2021 | 13.815687001566 | 2020 | 14.541582422103 | 2019 | 11.374994176691 | 2018 | 11.882586731913 | 2017 | 12.897440497405 | 2016 | 14.286149135706 | 2015 | 14.944264787853 | 2014 | 14.181250488571 | 2013 | 14.247055690954 | 2012 | 13.725717975884 | 2011 | 15.126031065005 | 2010 | 14.590404710658 | 2009 | 13.330941033578 | 2008 | 10.966289773973 | 2007 | 14.072262705919 | 2006 | 15.44185523096 | 2005 | 15.500854965938 | 2004 | 17.7113344797 | 2003 | 18.572287717875 | 2002 | 18.678025806599 | 2001 | 17.043271611584 | 2000 | 16.263070578526 | 1999 | 16.702325876274 | 1998 | 17.367261955979 | 1997 | 16.040840753997 | 1996 | 15.606998845259 | 1995 | 17.112991243706 | 1994 | 19.112776837281 | 1993 | 16.126981437924 | 1992 | 21.466480517327 | 1991 | 21.36395517204 | 1990 | 18.02974964612 | 1989 | 17.232679131441 | 1988 | 17.394045637872 | 1987 | 20.396776523801 | 1986 | 18.895094514271 | 1985 | 14.596717431294 | 1984 | 17.050660058707 | 1983 | 18.86861578191 | 1982 | 17.620499690649 | 1981 | 17.46949538417 | 1980 | 16.422234032241 | 1979 | 14.095992519095 | 1978 | 15.535363118842 | 1977 | 15.305610310604 | 1976 | 13.127450741923 |
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