Year | Value | 2022 | 15.946297735285 | 2021 | 17.401875558104 | 2020 | 14.793333920498 | 2019 | 12.250795843098 | 2018 | 12.707419953344 | 2017 | 13.577769686877 | 2016 | 13.421753005251 | 2015 | 14.529347178498 | 2014 | 16.134405000483 | 2013 | 18.15169082519 | 2012 | 17.678108528341 | 2011 | 18.60126643343 | 2010 | 17.802399379775 | 2009 | 16.380365067051 | 2008 | 19.226846634159 | 2007 | 19.346360326195 | 2006 | 18.409816355955 | 2005 | 18.114095552395 | 2004 | 18.855018861685 | 2003 | 16.41794180867 | 2002 | 15.405872269644 | 2001 | 13.59459737532 | 2000 | 13.991703128315 | 1999 | 12.73690145125 | 1998 | 13.89045293941 | 1997 | 13.711158574772 | 1996 | 14.041321016101 | 1995 | 14.439362707423 | 1994 | 19.097427357209 | 1993 | 20.184838177731 | 1992 | 20.091829459241 | 1991 | 18.662661314401 | 1990 | 18.921261676268 | 1989 | 35.806970927174 | 1988 | 25.624126920404 | 1987 | 22.636579816495 | 1986 | 17.870324439312 | 1985 | 20.113449887029 | 1984 | 17.402664066568 | 1983 | 14.217290137212 | 1982 | 15.882598963027 | 1981 | 18.96771523306 | 1980 | 17.628920504359 | 1979 | 18.330850090308 | 1978 | 19.484443208276 | 1977 | 19.728142396961 | 1976 | 19.138175338353 | 1975 | 20.589150450095 |
|