Year | Value | 2021 | 51.414673692744 | 2020 | 49.233887312525 | 2019 | 48.317794892582 | 2018 | 50.060802594244 | 2017 | 52.249695987029 | 2016 | 52.209160924199 | 2015 | 52.209160924199 | 2014 | 52.16862586137 | 2013 | 51.114714227807 | 2012 | 50.060802594244 | 2011 | 49.04742602351 | 2010 | 47.993514389947 | 2009 | 46.939602756384 | 2008 | 45.885691122821 | 2007 | 45.804620997163 | 2006 | 45.683015808674 | 2005 | 45.561410620186 | 2004 | 45.439805431698 | 2003 | 45.35873530604 | 2002 | 45.237130117552 | 2001 | 44.588569112282 | 2000 | 40.535062829347 | 1999 | 35.103364410215 | 1998 | 33.238751520065 | 1997 | 32.428050263478 | 1996 | 30.401297122011 | 1995 | 28.374543980543 | 1994 | 28.374543980543 | 1993 | 34.454803404945 | 1992 | 35.670855289826 | 1991 | 35.670855289826 | 1990 | 35.670855289826 | 1989 | 34.454803404945 | 1988 | 34.414268342116 | 1987 | 34.130522902311 | 1986 | 33.806242399676 | 1985 | 33.52249695987 | 1984 | 33.238751520065 | 1983 | 32.630725577625 | 1982 | 32.022699635184 | 1981 | 31.414673692744 | 1980 | 30.806647750304 | 1979 | 30.198621807864 | 1978 | 29.590595865424 | 1977 | 28.982569922983 | 1976 | 28.374543980543 | 1975 | 27.807053100932 | 1974 | 27.077421970004 | 1973 | 24.726388325902 | 1972 | 25.172274017025 | 1971 | 22.699635184434 | 1970 | 21.159302796919 | 1969 | 21.402513173895 | 1968 | 21.11876773409 | 1967 | 20.875557357114 | 1966 | 20.672882042967 | 1965 | 20.47020672882 | 1964 | 20.267531414674 | 1963 | 20.064856100527 | 1962 | 19.86218078638 | 1961 | 19.659505472234 |
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