| Year | Value | | 2022 | 0.31544223461573 | | 2021 | 0.49845744017811 | | 2020 | 0.27836363239622 | | 2019 | 0.67056741675877 | | 2018 | 0.97233788001974 | | 2017 | 0.52801877204323 | | 2016 | 0.56293758465864 | | 2015 | 0.60656918409079 | | 2014 | 0.63285782111929 | | 2013 | 0.66141947322301 | | 2012 | 0.63368452223531 | | 2011 | 0.57005368603976 | | 2010 | 0.57706224943426 | | 2009 | 0.58227097813321 | | 2008 | 0.5696540374642 | | 2007 | 0.5920648235151 | | 2006 | 0.6131445706371 | | 2005 | 0.62277637976136 | | 2004 | 0.64949595391937 | | 2003 | 0.673052509337 | | 2002 | 0.67964899514894 | | 2001 | 0.67853301835983 | | 2000 | 0.71521264424712 | | 1999 | 0.78505764214067 | | 1998 | 0.83226960042879 | | 1997 | 0.85476827678033 | | 1996 | 0.90114481850432 | | 1995 | 0.92263433318259 | | 1994 | 0.88562901023479 | | 1993 | 0.88327672699187 | | 1992 | 0.85601928981825 | | 1991 | 0.69954023185836 | | 1990 | 0.62210327814691 | | 1989 | 0.66905548167497 | | 1988 | 0.68915599604608 | | 1987 | 0.76421779138242 | | 1986 | 0.89752411861772 | | 1985 | 0.96922128726442 | | 1984 | 1.0183048342767 | | 1983 | 1.0819140829197 | | 1982 | 1.1003492855134 | | 1981 | 1.0916726926345 | | 1980 | 1.0414775804842 | | 1979 | 1.0068439765532 | | 1978 | 1.0220627110855 | | 1977 | 1.033053309286 | | 1976 | 1.0615843082926 | | 1975 | 1.1025267309458 | | 1974 | 1.1421280617958 | | 1973 | 1.1801647605958 | | 1972 | 1.3172299634784 | | 1971 | 1.4245412263386 | | 1970 | 1.4219467029002 | | 1969 | 1.4522353539437 | | 1968 | 1.494923206635 | | 1967 | 1.5541921414677 | | 1966 | 1.6147964262131 | | 1965 | 1.6735197513954 | | 1964 | 1.7339312944803 | | 1963 | 1.7662982489087 | | 1962 | 1.794900906391 | | 1961 | 1.9074675806774 |
|