Year | Value | 2022 | 1.8988243477779 | 2021 | 1.9891227003582 | 2020 | 2.0106400988588 | 2019 | 1.8810434541849 | 2018 | 1.89567007851 | 2017 | 2.0042340765763 | 2016 | 2.0885308793071 | 2015 | 1.9536335918401 | 2014 | 1.7730588775679 | 2013 | 1.6391801995446 | 2012 | 1.6709639653849 | 2011 | 1.7556569466072 | 2010 | 1.8529282576867 | 2009 | 1.9239383339401 | 2008 | 1.7966880893184 | 2007 | 1.812273234227 | 2006 | 1.8223309260448 | 2005 | 1.8024926795994 | 2004 | 1.8274107694049 | 2003 | 1.8462896887145 | 2002 | 1.8739646206139 | 2001 | 1.8700938789187 | 2000 | 1.8298419125101 | 1999 | 1.8892357407291 | 1998 | 1.8711218131061 | 1997 | 1.8673343949934 | 1996 | 1.9304400674052 | 1995 | 2.0213125680433 | 1994 | 2.1165985889343 | 1993 | 2.1780298864631 | 1992 | 2.1687460801263 | 1991 | 2.1680428583108 | 1990 | 2.0759058597177 | 1989 | 2.0518275094775 | 1988 | 2.1618148826629 | 1987 | 2.3729888324139 | 1986 | 2.5404297515787 | 1985 | 2.5232683787052 | 1984 | 2.5052336507001 | 1983 | 2.5198118191653 | 1982 | 2.3932652161369 | 1981 | 2.2966019447106 | 1980 | 2.2489569040352 | 1979 | 2.1927293710329 | 1978 | 2.2156885699106 | 1977 | 2.2472022083371 | 1976 | 2.2166121067525 | 1975 | 2.2673155925373 | 1974 | 2.2628026994839 | 1973 | 2.3793467959466 | 1972 | 2.6856206048579 | 1971 | 2.7631517088994 | 1970 | 2.966035576823 | 1969 | 3.3859198800219 | 1968 | 3.8372735845989 | 1967 | 3.7937639672236 | 1966 | 3.451382903706 | 1965 | 2.952292961532 | 1964 | 2.648242797051 | 1963 | 2.4466346391957 | 1962 | 2.3636953699697 | 1961 | 2.4151398541152 | 1960 | 2.3695451396906 |
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