| Year | Value | | 2022 | 0.8410582436777 | | 2021 | 0.99892041856304 | | 2020 | 1.2231792951145 | | 2019 | 1.2950738629213 | | 2018 | 1.2255300399434 | | 2017 | 0.38727848785736 | | 2016 | 0.97200398206436 | | 2015 | 2.0740168585351 | | 2014 | 1.5762942213257 | | 2013 | 1.3616211070758 | | 2012 | 1.3291585245518 | | 2011 | 1.2634056181143 | | 2010 | 1.1930360036351 | | 2009 | 1.1892950701333 | | 2008 | 1.1330813387092 | | 2007 | 1.0138772126755 | | 2006 | 0.9635934578021 | | 2005 | 0.94509424081772 | | 2004 | 0.93529016888796 | | 2003 | 0.92420937280869 | | 2002 | 0.91010094302254 | | 2001 | 0.88566041220439 | | 2000 | 0.96286402557088 | | 1999 | 1.1115545448798 | | 1998 | 1.2445526809947 | | 1997 | 1.3862772595191 | | 1996 | 1.5240828018565 | | 1995 | 1.6460395410098 | | 1994 | 1.7310430672935 | | 1993 | 1.8145462170322 | | 1992 | 2.0559049545017 | | 1991 | 2.5583962929086 | | 1990 | 3.0783936947649 | | 1989 | 3.3523740867702 | | 1988 | 3.4678070468829 | | 1987 | 3.4976763665857 | | 1986 | 3.2783262804111 | | 1985 | 2.9609489148854 | | 1984 | 2.794499448333 | | 1983 | 2.680367986685 | | 1982 | 2.5790549814137 | | 1981 | 2.5765650160928 | | 1980 | 2.6360796669513 | | 1979 | 2.6610429384582 | | 1978 | 2.697162875456 | | 1977 | 2.6809957092095 | | 1976 | 2.688104186784 | | 1975 | 2.756828902215 | | 1974 | 2.8085534386606 | | 1973 | 2.8454144656995 | | 1972 | 2.85517679409 | | 1971 | 2.921523621994 | | 1970 | 3.0138610973662 | | 1969 | 3.0580222235671 | | 1968 | 3.0868066719664 | | 1967 | 3.0892958239573 | | 1966 | 3.0922110709255 | | 1965 | 3.0915005102493 | | 1964 | 3.061378243262 | | 1963 | 3.0334396325203 | | 1962 | 2.9786506260395 | | 1961 | 2.7994924565016 |
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