Year | Value | 2014 | 49.834183800871 | 2013 | 49.049935824054 | 2012 | 47.915744817889 | 2011 | 48.196431617312 | 2010 | 47.569540627327 | 2009 | 48.102656841714 | 2008 | 48.86697270913 | 2007 | 49.374818673904 | 2006 | 47.903223415655 | 2005 | 46.915447557008 | 2004 | 47.463541561611 | 2003 | 56.386516829149 | 2002 | 53.817096604906 | 2001 | 56.465183984934 | 2000 | 57.605554596629 | 1999 | 60.590171118507 | 1998 | 63.757671909287 | 1997 | 58.437987847272 | 1996 | 57.706073812265 | 1995 | 59.389898979616 | 1994 | 57.374567811033 | 1993 | 58.302678701648 | 1992 | 58.857969627083 | 1991 | 59.494607513748 | 1990 | 59.349374907969 | 1989 | 59.143313518039 | 1988 | 55.677583500992 | 1987 | 55.730670999381 | 1986 | 53.838641362019 | 1985 | 52.628951338983 | 1984 | 48.828207393895 | 1983 | 49.233285066706 | 1982 | 54.163650158655 | 1981 | 56.106880579232 | 1980 | 60.474663072133 | 1979 | 64.906359068445 | 1978 | 65.533904935028 | 1977 | 64.922029743226 | 1976 | 59.440012435754 | 1975 | 61.106985260496 | 1974 | 59.198649100326 | 1973 | 60.980446240206 | 1972 | 58.425250139643 | 1971 | 58.284087013451 |
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