Year | Value | 2022 | 2.8340436713195 | 2021 | 3.4378762523237 | 2020 | 3.4257337002299 | 2019 | 2.7524705308083 | 2018 | 2.8235955372865 | 2017 | 3.0286011137381 | 2016 | 2.5861308735712 | 2015 | 2.3601744519979 | 2014 | 1.5159338319542 | 2013 | 1.1613791316063 | 2012 | 1.1964057452663 | 2011 | 1.2410333300729 | 2010 | 1.374566808201 | 2009 | 1.4186642547988 | 2008 | 1.4657148680742 | 2007 | 1.35503402826 | 2006 | 1.3914154103969 | 2005 | 1.3843120409343 | 2004 | 1.4219988436264 | 2003 | 1.4193331132051 | 2002 | 1.2688504314445 | 2001 | 1.2951722279003 | 2000 | 1.4786497444575 | 1999 | 1.4922899278834 | 1998 | 1.4046323108263 | 1997 | 1.4968522377367 | 1996 | 1.4284105941625 | 1995 | 1.4970170822989 | 1994 | 1.4380262656364 | 1993 | 1.5637934650809 | 1990 | 1.9564941828743 | 1989 | 2.1120113100361 | 1988 | 2.2134681020672 | 1987 | 2.1167861138831 | 1986 | 2.0267689405455 | 1985 | 2.1424163258519 | 1984 | 1.9726074138051 | 1983 | 1.9836600862309 | 1982 | 2.1067949567238 | 1981 | 1.960761961218 | 1980 | 2.0792956065254 | 1979 | 2.9661016949152 | 1978 | 3.2139577594123 | 1977 | 3.1295843520782 | 1976 | 2.9115341545353 | 1975 | 3.1660231660232 | 1974 | 2.8659160696008 | 1973 | 2.6558089033659 | 1972 | 2.3755656108597 | 1971 | 1.9161676646707 | 1970 | 2.2280471821756 | 1969 | 2.1755162241888 | 1968 | 1.9908116385911 | 1967 | 2.4038461538462 | 1966 | 2.4080338266385 | 1965 | 2.5199115044248 | 1964 | 2.868778280543 | 1963 | 2.6469135802469 | 1962 | 2.8913043478261 | 1961 | 2.7022471910112 |
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