Year | Value | 2021 | 40.484425266533 | 2020 | 40.484425266533 | 2019 | 40.484425266533 | 2018 | 39.988141901907 | 2017 | 39.702669170043 | 2016 | 39.668632036628 | 2015 | 39.633496931168 | 2014 | 39.599459797754 | 2013 | 39.564324692293 | 2012 | 39.530287558879 | 2011 | 39.495152453418 | 2010 | 39.461115320004 | 2009 | 40.484425266533 | 2008 | 39.391943081129 | 2007 | 39.356807975669 | 2006 | 39.322770842254 | 2005 | 39.287635736794 | 2004 | 39.25359860338 | 2003 | 39.218463497919 | 2002 | 39.184426364505 | 2001 | 39.143801398816 | 2000 | 38.42902159711 | 1999 | 38.42902159711 | 1998 | 37.331049551478 | 1997 | 36.452671914973 | 1996 | 36.34287471041 | 1995 | 36.123280301284 | 1994 | 34.037133414583 | 1993 | 33.048958573515 | 1992 | 33.048958573515 | 1991 | 31.84118932332 | 1990 | 30.824467209065 | 1989 | 30.620244408577 | 1988 | 30.427001328546 | 1987 | 30.174467758051 | 1986 | 30.040515168484 | 1985 | 29.879113277776 | 1984 | 29.716613415023 | 1983 | 29.555211524315 | 1982 | 29.393809633607 | 1981 | 29.231309770853 | 1980 | 29.069907880145 | 1979 | 28.907408017392 | 1978 | 28.746006126684 | 1977 | 28.584604235976 | 1976 | 28.422104373223 | 1975 | 28.260702482515 | 1974 | 28.099300591807 | 1973 | 27.936800729053 | 1972 | 27.775398838346 | 1971 | 27.613996947638 | 1970 | 27.451497084884 | 1969 | 27.290095194176 | 1968 | 27.128693303468 | 1967 | 26.966193440715 | 1966 | 26.804791550007 | 1965 | 26.642291687254 | 1964 | 26.480889796546 | 1963 | 26.319487905838 | 1962 | 26.156988043084 | 1961 | 25.995586152377 |
|