Year | Value | 2022 | 2.3929723009355 | 2021 | 2.3400338207819 | 2020 | 2.461628767683 | 2019 | 2.2692000368406 | 2018 | 2.1836351427121 | 2017 | 2.1724872532341 | 2016 | 2.2086675995939 | 2015 | 2.2242993410167 | 2014 | 2.226360552753 | 2013 | 2.3294051038541 | 2012 | 2.4677353457808 | 2011 | 2.5518677394518 | 2010 | 2.6504705335085 | 2009 | 2.6959803874646 | 2008 | 2.4570313037047 | 2007 | 2.3606394200883 | 2006 | 2.3876504249469 | 2005 | 2.4006956697999 | 2004 | 2.395828739207 | 2003 | 2.3775198494897 | 2002 | 2.2789586085903 | 2001 | 2.1465375573717 | 2000 | 2.1196657288984 | 1999 | 2.1261638652022 | 1998 | 2.1841012624937 | 1997 | 2.2347088242421 | 1996 | 2.2623331536374 | 1995 | 2.3166804977517 | 1994 | 2.5005610824106 | 1993 | 2.6845320177662 | 1992 | 2.8545637760804 | 1991 | 2.897701585391 | 1990 | 3.2316352501082 | 1989 | 3.3876333181528 | 1988 | 3.4534712174382 | 1987 | 3.7145520932349 | 1986 | 3.9470334557516 | 1985 | 4.1697712936643 | 1984 | 4.0683228401455 | 1983 | 4.0536601660172 | 1982 | 4.1929565751333 | 1981 | 3.6132705186926 | 1980 | 3.369018316125 | 1979 | 3.3091792745159 | 1978 | 3.3194782214324 | 1977 | 3.4963021270595 | 1976 | 3.5324319142495 | 1975 | 3.7276269154252 | 1974 | 3.8225027913174 | 1973 | 3.8295501945512 | 1972 | 4.2960412506504 | 1971 | 4.5914504043805 | 1970 | 5.1312175308804 | 1969 | 5.8530826006036 | 1968 | 6.3447308935328 | 1967 | 6.4726694256395 | 1966 | 6.0165786783894 | 1965 | 5.6194224292495 | 1964 | 5.9198541417757 | 1963 | 6.4491393812522 | 1962 | 6.8616382555076 | 1961 | 6.7906577424061 | 1960 | 6.8233780627818 |
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