Year | Value | 2022 | 37.247460647309 | 2021 | 33.109288775584 | 2020 | 30.602208468684 | 2019 | 30.343874850502 | 2018 | 29.87983949006 | 2017 | 30.061553689247 | 2016 | 29.545033710093 | 2015 | 28.873959845414 | 2014 | 29.003611726613 | 2013 | 27.452070948464 | 2012 | 25.741771002222 | 2011 | 25.715205656374 | 2010 | 24.627494027749 | 2009 | 22.566535666819 | 2008 | 26.888327440674 | 2007 | 26.740654013268 | 2006 | 27.646185031185 | 2005 | 26.40806444137 | 2004 | 25.808668705092 | 2003 | 25.200286925891 | 2002 | 25.258394560966 | 2001 | 25.929894171042 | 2000 | 24.949581852804 | 1999 | 24.297128000135 | 1998 | 23.47005794134 | 1997 | 23.841003230768 | 1996 | 22.934326658933 | 1995 | 22.839704020191 | 1994 | 21.670270488835 | 1993 | 22.014878407639 | 1992 | 22.147325597708 | 1991 | 21.647248033359 | 1990 | 22.651464912605 | 1989 | 21.462571604922 | 1988 | 21.207089698219 | 1987 | 21.065186494471 | 1986 | 20.040426647885 | 1985 | 18.789984722791 | 1984 | 18.606103546531 | 1983 | 16.92584696967 | 1982 | 15.259587392857 | 1981 | 15.249845634083 | 1980 | 18.108455982467 | 1979 | 20.593685466227 | 1978 | 22.1731628453 | 1977 | 21.762860164319 | 1976 | 21.060172501229 | 1975 | 21.215436733963 |
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