Year | Value | 2022 | 28.484487199309 | 2021 | 27.549435833939 | 2020 | 27.694719000954 | 2019 | 28.623729804485 | 2018 | 30.058473929663 | 2017 | 30.435829832651 | 2016 | 30.582731976415 | 2015 | 31.148807691616 | 2014 | 31.951701076119 | 2013 | 32.762992997637 | 2012 | 33.550264308865 | 2011 | 33.339332019448 | 2010 | 34.373494092864 | 2009 | 33.40376376356 | 2008 | 33.390033852123 | 2007 | 34.319022883629 | 2006 | 33.837644762753 | 2005 | 32.128748616225 | 2004 | 31.33177053539 | 2003 | 29.004641692874 | 2002 | 27.174518821159 | 2001 | 25.370094361634 | 2000 | 25.142403929186 | 1999 | 24.746675242402 | 1998 | 24.92502161093 | 1997 | 25.990167694028 | 1996 | 25.452730333497 | 1995 | 25.443124889217 | 1994 | 24.888261659308 | 1993 | 23.073030189397 | 1992 | 22.948320587916 | 1991 | 21.743720989183 | 1990 | 21.016304676626 | 1989 | 20.065984244527 | 1988 | 18.541329064968 | 1987 | 17.928300870871 | 1986 | 16.822731534582 | 1985 | 17.152834708051 | 1984 | 16.201924593216 | 1983 | 16.579794881962 | 1982 | 16.914751052071 | 1981 | 16.688811226798 | 1980 | 14.617377149993 | 1979 | 15.192771959944 | 1978 | 14.331974388762 | 1977 | 14.719777463328 | 1976 | 14.084198085974 | 1975 | 12.896893270935 |
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