Year | Value | 2021 | 1.8827543939342 | 2020 | 1.8668436070412 | 2019 | 1.8627776828431 | 2018 | 1.8951748750022 | 2017 | 1.911916518128 | 2016 | 1.9949404751832 | 2015 | 2.0115887443703 | 2014 | 1.9963747228883 | 2013 | 1.9516759301458 | 2012 | 1.92706289856 | 2011 | 1.8654522876578 | 2010 | 1.8640190198032 | 2009 | 1.8652959128979 | 2008 | 1.8522037854325 | 2007 | 1.7810957059707 | 2006 | 1.7136743152717 | 2005 | 1.6814747782854 | 2004 | 1.7075529603547 | 2003 | 1.6686676188682 | 2002 | 1.6662684104138 | 2001 | 1.6674258743456 | 2000 | 1.665584421674 | 1999 | 1.6745617654655 | 1998 | 1.7348299848795 | 1997 | 1.7769980062309 | 1996 | 1.8483677124238 | 1995 | 1.9211807064561 | 1994 | 1.976402902527 | 1993 | 2.0224742493014 | 1992 | 2.1487894913736 | 1991 | 2.2835385283037 | 1990 | 2.3742288144411 | 1989 | 2.4732140397473 | 1988 | 2.5691590130103 | 1987 | 2.6423111570602 | 1986 | 2.6394143426486 | 1985 | 2.6013515598647 | 1984 | 2.634577565284 | 1983 | 2.659850622887 | 1982 | 2.6245369368326 | 1981 | 2.5674808263396 | 1980 | 2.578037352333 | 1979 | 2.606939457861 | 1978 | 2.6358309915928 | 1977 | 2.6671255483443 | 1976 | 2.7117115400348 | 1975 | 2.7418994847472 | 1974 | 2.7766459801163 | 1973 | 2.7943851553003 | 1972 | 2.8272402156338 | 1971 | 2.8372467895828 | 1970 | 2.822321092136 | 1969 | 2.8142629837304 | 1968 | 2.8197767526186 | 1967 | 2.8530655035045 | 1966 | 2.9053769976411 | 1965 | 2.9324597416348 | 1964 | 2.9619743430377 | 1963 | 3.0335360250406 | 1962 | 3.0953290620139 | 1961 | 3.1461434356504 | 1960 | 3.184230068362 |
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