Year | Value | 2022 | 1.9389829438239 | 2021 | 2.0077448703116 | 2020 | 2.0662688007702 | 2019 | 2.0889311840129 | 2018 | 2.1226797659381 | 2017 | 2.2349454287196 | 2016 | 2.3393832589699 | 2015 | 2.3642697591032 | 2014 | 2.4076448920626 | 2013 | 2.4524272555353 | 2012 | 2.4605958404428 | 2011 | 2.4381816301997 | 2010 | 2.4699961671729 | 2009 | 2.5355049203182 | 2008 | 2.5723272222071 | 2007 | 2.6054637855072 | 2006 | 2.6391614616194 | 2005 | 2.6598948801039 | 2004 | 2.6689092702209 | 2003 | 2.7144328205261 | 2002 | 2.7483799172502 | 2001 | 2.6597686890759 | 2000 | 2.5165187385172 | 1999 | 2.4391006983111 | 1998 | 2.41566538352 | 1997 | 2.3485207263226 | 1996 | 2.2966025502034 | 1995 | 2.3088214660063 | 1994 | 2.3585896626621 | 1993 | 2.4455090501712 | 1992 | 2.4815159218942 | 1991 | 2.5343846712328 | 1990 | 2.5873075116156 | 1989 | 2.5621668790606 | 1988 | 2.490510235576 | 1987 | 2.398123131385 | 1986 | 2.3187336550931 | 1985 | 2.2891775433982 | 1984 | 2.722553539322 | 1983 | 3.122419794884 | 1982 | 3.0006038568251 | 1981 | 2.8884060063181 | 1980 | 2.9904472174879 | 1979 | 3.1083809146282 | 1978 | 3.0721248900398 | 1977 | 2.9671488877796 | 1976 | 2.8879859122063 | 1975 | 2.8902752087719 | 1974 | 2.8819693906215 | 1973 | 2.85493128782 | 1972 | 2.7831443502552 | 1971 | 2.7488917959869 | 1970 | 2.6532921265687 | 1969 | 2.4837376369327 | 1968 | 2.4296386778664 | 1967 | 2.4198162374548 | 1966 | 2.4223731211352 | 1965 | 2.4248789066674 | 1964 | 2.4103393612003 | 1963 | 2.4025278618606 | 1962 | 2.3928918793933 | 1961 | 2.8177528489928 |
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