Year | Value | 2022 | 30.051936431505 | 2021 | 30.622516181243 | 2020 | 27.076065176799 | 2019 | 26.389994464717 | 2018 | 27.98549465352 | 2017 | 26.055944934538 | 2016 | 24.980196711573 | 2015 | 25.212570497271 | 2014 | 24.899965698669 | 2013 | 23.911721230966 | 2012 | 23.380427048953 | 2011 | 23.027247490471 | 2010 | 21.797666856269 | 2009 | 21.949671599606 | 2008 | 24.620391750435 | 2007 | 23.912277631309 | 2006 | 24.626726946558 | 2005 | 23.640346973994 | 2004 | 22.30676868957 | 2003 | 20.653695032499 | 2002 | 22.452632426908 | 2001 | 21.520064142206 | 2000 | 21.404012716231 | 1999 | 21.819944632185 | 1998 | 25.731235828247 | 1997 | 20.492078130626 | 1996 | 21.800704445056 | 1995 | 19.609096533248 | 1994 | 18.191319313568 | 1993 | 18.513951818464 | 1992 | 18.348793818733 | 1991 | 18.552669829995 | 1990 | 21.691362213727 | 1989 | 26.076821038175 | 1988 | 28.425803868462 | 1987 | 24.17165444535 | 1986 | 38.402917512574 | 1985 | 34.82273303415 | 1984 | 29.402417668693 | 1983 | 28.80582142703 | 1982 | 31.864351766074 | 1981 | 32.512850274649 | 1980 | 28.824330340687 | 1979 | 33.705711097513 | 1978 | 30.930643321322 | 1977 | 31.931007554672 | 1976 | 34.099134475219 | 1975 | 32.787697538008 | 1974 | 32.149033128278 |
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