Year | Value | 2022 | 12.754077143768 | 2021 | 10.85402573877 | 2020 | 13.453391834346 | 2019 | 17.172424731951 | 2018 | 16.082778106382 | 2017 | 12.476527694959 | 2016 | 9.7100415221082 | 2015 | 9.5934647080486 | 2014 | 11.884960798122 | 2013 | 13.683221619007 | 2012 | 12.87821102287 | 2011 | 16.868718255415 | 2010 | 17.950388944141 | 2009 | 16.839842064863 | 2008 | 23.623500837521 | 2007 | 23.555298200859 | 2006 | 22.976736279747 | 2005 | 21.842292107707 | 2004 | 21.112219245827 | 2003 | 18.648095808383 | 2002 | 18.407987595672 | 2001 | 18.610671034291 | 2000 | 17.583873419582 | 1999 | 18.895144213264 | 1998 | 18.959359777314 | 1997 | 17.736939827003 | 1996 | 18.751829816914 | 1995 | 22.243441960784 | 1994 | 23.926628114286 | 1993 | 31.625027835052 | 1992 | 35.475630553559 | 1991 | 34.927901155556 | 1990 | 31.684120354906 | 1989 | 26.357651782763 | 1988 | 27.365842486085 | 1987 | 25.990514563107 | 1986 | 20.259395626822 | 1985 | 22.855612830333 | 1984 | 27.647629439149 | 1983 | 28.033866454728 | 1982 | 22.056928673309 | 1981 | 22.120247797287 | 1980 | 21.314321993389 | 1979 | 22.563102504315 | 1978 | 24.406608816642 | 1977 | 20.806308958787 |
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