| Year | Value | | 2022 | 0.37756453145943 | | 2021 | 0.15674705475018 | | 2020 | 0.9643479001932 | | 2019 | 0.45538128596354 | | 2018 | 0.52643539556405 | | 2017 | 0.63264399508256 | | 2016 | 0.72467606745143 | | 2015 | 0.73621730882542 | | 2014 | 0.73336151993742 | | 2013 | 0.69286027662458 | | 2012 | 0.73359994125085 | | 2011 | 0.72678670481075 | | 2010 | 0.8296166747098 | | 2009 | 0.87665129880291 | | 2008 | 0.94586528728259 | | 2007 | 0.95105524277243 | | 2006 | 0.96425391713608 | | 2005 | 0.92171316716121 | | 2004 | 0.92548396894348 | | 2003 | 0.85948171284095 | | 2002 | 0.92779748571031 | | 2001 | 0.98974138222367 | | 2000 | 1.1127689967953 | | 1999 | 1.1483400472906 | | 1998 | 1.1657145264259 | | 1997 | 1.2039602970127 | | 1996 | 1.1634116199819 | | 1995 | 1.1907870909021 | | 1994 | 1.2262960888682 | | 1993 | 1.3186799997774 | | 1992 | 1.3868856924794 | | 1991 | 1.3362607407378 | | 1990 | 1.1296505204558 | | 1989 | 0.94440555542853 | | 1988 | 0.90799904016768 | | 1987 | 0.89382920103205 | | 1986 | 0.92416415705898 | | 1985 | 0.88612904085088 | | 1984 | 0.86581733630996 | | 1983 | 0.91437851337515 | | 1982 | 0.95331756616351 | | 1981 | 0.98141543725968 | | 1980 | 0.95958992276448 | | 1979 | 1.103576565099 | | 1978 | 1.0595730803427 | | 1977 | 1.0057719961813 | | 1976 | 0.95022004899452 | | 1975 | 0.98598606734713 | | 1974 | 0.91366019606771 | | 1973 | 0.9544767285523 | | 1972 | 1.0705227523727 | | 1971 | 1.2643336918509 | | 1970 | 1.1650026668729 | | 1969 | 0.97724281187247 | | 1968 | 0.99846104358534 | | 1967 | 1.0888812072876 | | 1966 | 1.1548931907552 | | 1965 | 1.2501716456284 | | 1964 | 1.3890460551837 | | 1963 | 1.4391647617068 | | 1962 | 1.5379973582539 | | 1961 | 1.6577300373895 |
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