Year | Value | 2022 | 49.918165606351 | 2021 | 49.918930833015 | 2020 | 49.917554909787 | 2019 | 49.913965578512 | 2018 | 49.91072079406 | 2017 | 49.906539305068 | 2016 | 49.899734307371 | 2015 | 49.891972666243 | 2014 | 49.884252009437 | 2013 | 49.876385013046 | 2012 | 49.867048239132 | 2011 | 49.855084428488 | 2010 | 49.842119450065 | 2009 | 49.829676011422 | 2008 | 49.817087980767 | 2007 | 49.803685532408 | 2006 | 49.78895716946 | 2005 | 49.773029330882 | 2004 | 49.756274406194 | 2003 | 49.738244267948 | 2002 | 49.720197225747 | 2001 | 49.704138171716 | 2000 | 49.690500475858 | 1999 | 49.683365043168 | 1998 | 49.683034965382 | 1997 | 49.678309961498 | 1996 | 49.670097415741 | 1995 | 49.662271562157 | 1994 | 49.65877799886 | 1993 | 49.657250914183 | 1992 | 49.647526702278 | 1991 | 49.628820185492 | 1990 | 49.611595301972 | 1989 | 49.598459754833 | 1988 | 49.588431679288 | 1987 | 49.582486930262 | 1986 | 49.572626016266 | 1985 | 49.562328172918 | 1984 | 49.555237205786 | 1983 | 49.552254547791 | 1982 | 49.54716829728 | 1981 | 49.53815297535 | 1980 | 49.527124173743 | 1979 | 49.512973173468 | 1978 | 49.498443694584 | 1977 | 49.483127464377 | 1976 | 49.466971533007 | 1975 | 49.450373208037 | 1974 | 49.432956050254 | 1973 | 49.419468845715 | 1972 | 49.412746194982 | 1971 | 49.405956158832 | 1970 | 49.39670702437 | 1969 | 49.387438403296 | 1968 | 49.377947477438 | 1967 | 49.368600608919 | 1966 | 49.360176042663 | 1965 | 49.35243473557 | 1964 | 49.343971929959 | 1963 | 49.335639782363 | 1962 | 49.32658846922 | 1961 | 49.315525602974 | 1960 | 49.306297035883 |
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