Year | Value | 2022 | 1.418960371433 | 2021 | 1.3242271015704 | 2020 | 1.3753489449329 | 2019 | 1.2950923811542 | 2018 | 1.2775392718521 | 2017 | 1.1382332544705 | 2016 | 1.1476376168109 | 2015 | 1.1114460115866 | 2014 | 1.1492732863459 | 2013 | 1.2272520003469 | 2012 | 1.3518189725594 | 2011 | 1.3135312852757 | 2010 | 1.3986217868925 | 2009 | 1.3501786253165 | 2008 | 1.3550045902737 | 2007 | 1.3072468293925 | 2006 | 1.3774920136359 | 2005 | 1.3114884999136 | 2004 | 1.4237042339281 | 2003 | 1.466851249799 | 2002 | 1.5081498520497 | 2001 | 1.532380720453 | 2000 | 1.4574440505474 | 1999 | 1.564854722554 | 1998 | 1.6080263881253 | 1997 | 1.6159612050651 | 1996 | 1.6448166584561 | 1995 | 1.6853146650741 | 1994 | 1.7701098833609 | 1993 | 1.9071976696874 | 1992 | 1.8893772853369 | 1991 | 1.9546801500063 | 1990 | 1.9507570350492 | 1989 | 2.0242201369516 | 1988 | 2.0874706324154 | 1987 | 2.0316474834314 | 1986 | 1.944819236688 | 1985 | 2.1046721071011 | 1984 | 2.2354707255298 | 1983 | 2.3647428760569 | 1982 | 2.4198950252068 | 1981 | 2.4386663920474 | 1980 | 2.3630925227056 | 1979 | 2.2515273723598 | 1978 | 2.2718211945282 | 1977 | 2.2163031285921 | 1976 | 2.204203184792 | 1975 | 2.3972495422619 | 1974 | 2.2348439315623 | 1973 | 1.9758075832842 | 1972 | 2.1799733458664 | 1971 | 2.3622221893622 | 1970 | 2.4291199659416 | 1969 | 2.3916076314025 | 1968 | 2.6759341499184 | 1967 | 2.5882109236541 | 1966 | 2.6367496989288 | 1965 | 2.832137733142 | 1964 | 2.8429144708215 | 1963 | 3.0415238937401 | 1962 | 3.0182731040925 | 1961 | 2.5868116450368 | 1960 | 2.7288775560241 |
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