Year | Value | 2022 | 22.094274109371 | 2021 | 22.346206815342 | 2020 | 21.089406844683 | 2019 | 22.934468500426 | 2018 | 22.346379440774 | 2017 | 22.176032838985 | 2016 | 21.919998013812 | 2015 | 21.008190654804 | 2014 | 19.577920916415 | 2013 | 19.253607549227 | 2012 | 18.516978316375 | 2011 | 17.855489343382 | 2010 | 18.64331656828 | 2009 | 19.224215113244 | 2008 | 19.560535872782 | 2007 | 21.013845618227 | 2006 | 21.715753260635 | 2005 | 22.123066771185 | 2004 | 22.807877665446 | 2003 | 23.62908281017 | 2002 | 22.964168663731 | 2001 | 22.081658768337 | 2000 | 22.329152262688 | 1999 | 22.288425056048 | 1998 | 22.701050225749 | 1997 | 22.068688563577 | 1996 | 20.999628545506 | 1995 | 21.314247472706 | 1994 | 18.705030732349 | 1993 | 19.18890925625 | 1992 | 19.343728027905 | 1991 | 21.197830425091 | 1990 | 21.805076573878 | 1989 | 22.297780638302 | 1988 | 22.835305464968 | 1987 | 21.689789970731 | 1986 | 21.791217748098 | 1985 | 20.874393527439 | 1984 | 20.07593850652 | 1983 | 18.392810160917 | 1982 | 18.559629564359 | 1981 | 18.485164465912 | 1980 | 20.480456656127 | 1979 | 22.572409554093 | 1978 | 23.535484975476 | 1977 | 22.930279774205 | 1976 | 22.515822577289 | 1975 | 25.09684156687 |
|