Year | Value | 2022 | 2.7177456962085 | 2021 | 2.809006119736 | 2020 | 2.8033217668726 | 2019 | 2.6712990779258 | 2018 | 2.4968437078958 | 2017 | 2.4214890007519 | 2016 | 2.4595778810827 | 2015 | 2.4949813645236 | 2014 | 2.529935780832 | 2013 | 2.5030090233387 | 2012 | 2.4992998805023 | 2011 | 2.4729555807131 | 2010 | 2.4627192027408 | 2009 | 2.603514106053 | 2008 | 2.489402768943 | 2007 | 2.4696388562827 | 2006 | 2.4883686698454 | 2005 | 2.4672827371857 | 2004 | 2.331064887845 | 2003 | 2.3286646177887 | 2002 | 2.3154743772762 | 2001 | 2.4278777409132 | 2000 | 2.4573175195553 | 1999 | 2.4925772197961 | 1998 | 2.794442003917 | 1997 | 2.6633878077206 | 1996 | 2.7434796633335 | 1995 | 2.8923329861881 | 1994 | 3.1927526689555 | 1993 | 3.4178948382391 | 1992 | 3.6902726902727 | 1991 | 3.7111278410797 | 1990 | 4.0023042892219 | 1989 | 4.2902352949115 | 1988 | 4.281215937992 | 1987 | 4.4686055504595 | 1986 | 4.9482562509422 | 1985 | 5.2255316846283 | 1984 | 5.2545353927751 | 1983 | 5.726813608425 | 1982 | 6.2408944853421 | 1981 | 6.4158572978266 | 1980 | 6.398772113209 | 1979 | 5.5258765683501 | 1978 | 6.3714506191944 | 1977 | 6.0349391212282 | 1976 | 5.9081556838315 | 1975 | 4.8787164771561 | 1974 | 4.5414456277068 | 1973 | 4.0347321644386 | 1972 | 5.010068079394 | 1971 | 4.7349886064337 | 1970 | 4.403346543373 | 1969 | 4.6943948924984 | 1968 | 4.7306417965394 | 1967 | 4.6851425395061 | 1966 | 4.6888736934649 | 1965 | 4.4104748778349 | 1964 | 4.1344396006188 | 1963 | 4.8238590872698 | 1962 | 6.8671963677639 | 1961 | 6.726149622512 | 1960 | 7.1575483340189 |
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