Year | Value | 2022 | 51.503049598533 | 2021 | 51.480957710244 | 2020 | 51.468808599375 | 2019 | 51.328791694505 | 2018 | 51.07131952318 | 2017 | 50.831149214339 | 2016 | 50.608049475451 | 2015 | 50.402504164752 | 2014 | 50.316144704895 | 2013 | 50.337665136838 | 2012 | 50.359719732416 | 2011 | 50.381422921767 | 2010 | 50.400896753273 | 2009 | 50.416985196324 | 2008 | 50.429381376963 | 2007 | 50.437374521998 | 2006 | 50.437321922835 | 2005 | 50.440659188239 | 2004 | 50.453823415553 | 2003 | 50.469220989934 | 2002 | 50.484722711353 | 2001 | 50.501708739634 | 2000 | 50.523162992907 | 1999 | 50.54667978033 | 1998 | 50.571817064486 | 1997 | 50.598446616974 | 1996 | 50.629448944945 | 1995 | 50.666575749311 | 1994 | 50.704912163747 | 1993 | 50.743035239379 | 1992 | 50.785188365377 | 1991 | 50.83204835693 | 1990 | 50.821020118541 | 1989 | 50.747156007854 | 1988 | 50.699478298297 | 1987 | 50.679235712369 | 1986 | 50.624393517553 | 1985 | 50.532858138994 | 1984 | 50.437576930785 | 1983 | 50.340039716896 | 1982 | 50.190203486299 | 1981 | 50.069535699727 | 1980 | 50.030941032533 | 1979 | 49.991316824273 | 1978 | 49.942058896056 | 1977 | 49.898615144477 | 1976 | 49.743243511716 | 1975 | 49.497433854984 | 1974 | 49.425002278873 | 1973 | 49.436521559116 | 1972 | 49.448974746255 | 1971 | 49.461107218801 | 1970 | 49.472770700704 | 1969 | 49.484663849183 | 1968 | 49.496682787493 | 1967 | 49.5090781508 | 1966 | 49.521915544316 | 1965 | 49.536251254524 | 1964 | 49.554628553417 | 1963 | 49.57537644984 | 1962 | 49.598553107049 | 1961 | 49.624263811212 | 1960 | 49.649406148295 |
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