Year | Value | 2022 | 2.2660358063012 | 2021 | 2.3361575622483 | 2020 | 2.3619801976342 | 2019 | 2.3516473888838 | 2018 | 2.3276950835689 | 2017 | 2.3264753804576 | 2016 | 2.2908917067419 | 2015 | 2.2006987763436 | 2014 | 2.1614521168457 | 2013 | 2.1849523627332 | 2012 | 2.2855130551909 | 2011 | 2.3284505589173 | 2010 | 2.3083732819287 | 2009 | 2.2632483695447 | 2008 | 2.2786596369762 | 2007 | 2.3677803845677 | 2006 | 2.4063033728701 | 2005 | 2.3905080426586 | 2004 | 2.4118749454087 | 2003 | 2.5225503620296 | 2002 | 2.5125756437 | 2001 | 2.3569362743738 | 2000 | 2.347190218226 | 1999 | 2.3796916984148 | 1998 | 2.3696541269362 | 1997 | 2.4055953934977 | 1996 | 2.4702755593353 | 1995 | 2.5164528119722 | 1994 | 2.6076420184414 | 1993 | 2.73798612959 | 1992 | 2.6167360023607 | 1991 | 2.4266327325495 | 1990 | 2.4768524123813 | 1989 | 2.5019601134212 | 1988 | 2.4898700643617 | 1987 | 2.5443645578549 | 1986 | 2.5670818193516 | 1985 | 2.6382468143555 | 1984 | 2.6884393646707 | 1983 | 2.6942818870586 | 1982 | 2.5289247445195 | 1981 | 2.2708906525952 | 1980 | 2.388189902855 | 1979 | 2.6550595040798 | 1978 | 2.5934556581036 | 1977 | 2.438657231743 | 1976 | 2.425703501051 | 1975 | 2.5203015611851 | 1974 | 2.6024037719939 | 1973 | 2.5822305808869 | 1972 | 2.3488381485398 | 1971 | 2.3147343246553 | 1970 | 2.5779280462105 | 1969 | 2.6768061063504 | 1968 | 2.6959499268699 | 1967 | 2.6606297852543 | 1966 | 2.6290239383441 | 1965 | 2.6281189204243 | 1964 | 2.5975758837029 | 1963 | 2.5647800940882 | 1962 | 2.5504336115583 | 1961 | 2.5164380048311 |
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