Year | Value | 2022 | 21.940733190279 | 2021 | 20.108050240994 | 2020 | 20.457349614301 | 2019 | 24.272181887966 | 2018 | 23.70387103371 | 2017 | 25.152222448929 | 2016 | 23.883580721435 | 2015 | 22.207728990595 | 2014 | 23.384632383483 | 2013 | 23.889209993121 | 2012 | 22.27325948478 | 2011 | 22.42396597548 | 2010 | 21.179753890894 | 2009 | 19.627196342053 | 2008 | 14.784488172877 | 2007 | 9.6307333646782 | 2006 | 14.944679140628 | 2005 | 16.756853442118 | 2004 | 16.977015339125 | 2003 | 16.809831743862 | 2002 | 17.985153410415 | 2001 | 15.721540721082 | 2000 | 13.483798896628 | 1999 | 16.112580313853 | 1998 | 25.190229941423 | 1997 | 21.354719476941 | 1996 | 9.9566938269584 | 1995 | 25.565018017884 | 1994 | 8.5097488584475 | 1993 | 6.2155298093008 | 1992 | 12.823336653386 | 1991 | 17.337391304348 | 1990 | 14.655016677462 | 1989 | 28.825494198973 | 1988 | 32.677186915668 | 1987 | 30.333166353237 | 1986 | 32.12167163416 | 1985 | 31.849683850126 | 1984 | 35.329277033491 | 1983 | 33.762317790613 | 1982 | 34.924688932547 | 1981 | 36.061542885901 | 1980 | 29.676631383041 |
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