Year | Value | 2021 | 17.421441774492 | 2020 | 17.560073937153 | 2019 | 17.467652495379 | 2018 | 17.721811460259 | 2017 | 17.883548983364 | 2016 | 13.632162661737 | 2015 | 13.733826247689 | 2014 | 13.886321626617 | 2013 | 13.207024029575 | 2012 | 13.62292051756 | 2011 | 13.664510166359 | 2010 | 13.567467652495 | 2009 | 14.061922365989 | 2008 | 13.849353049908 | 2007 | 14.13123844732 | 2006 | 14.001848428835 | 2005 | 14.371534195933 | 2004 | 14.371534195933 | 2003 | 15.43438077634 | 2002 | 16.127541589649 | 2001 | 15.804066543438 | 2000 | 15.619223659889 | 1999 | 15.388170055453 | 1998 | 15.480591497227 | 1997 | 15.526802218115 | 1996 | 15.526802218115 | 1995 | 15.9426987061 | 1994 | 16.127541589649 | 1993 | 16.035120147874 | 1992 | 16.035120147874 | 1991 | 16.035120147874 | 1990 | 15.850277264325 | 1989 | 15.619223659889 | 1988 | 15.665434380776 | 1987 | 15.665434380776 | 1986 | 15.619223659889 | 1985 | 15.110905730129 | 1984 | 15.157116451017 | 1983 | 14.556377079482 | 1982 | 15.018484288355 | 1981 | 15.018484288355 | 1980 | 15.018484288355 | 1979 | 15.018484288355 | 1978 | 15.018484288355 | 1977 | 15.018484288355 | 1976 | 15.018484288355 | 1975 | 15.526802218115 | 1974 | 15.665434380776 | 1973 | 15.43438077634 | 1972 | 15.018484288355 | 1971 | 15.064695009242 | 1970 | 15.018484288355 | 1969 | 14.833641404806 | 1968 | 14.879852125693 | 1967 | 14.92606284658 | 1966 | 14.879852125693 | 1965 | 14.417744916821 | 1964 | 14.879852125693 | 1963 | 14.787430683919 | 1962 | 14.279112754159 | 1961 | 14.695009242144 |
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