Year | Value | 2015 | 50.088997205963 | 2014 | 47.051361174243 | 2013 | 51.519771321102 | 2012 | 50.277064576874 | 2011 | 51.367205990198 | 2010 | 51.780828025889 | 2009 | 52.599800169715 | 2008 | 52.182563938095 | 2007 | 50.847275339248 | 2006 | 54.693963100246 | 2005 | 57.560624680613 | 2004 | 53.722230846332 | 2003 | 52.744725444363 | 2002 | 52.962602151103 | 2001 | 52.64060607811 | 2000 | 51.927624548898 | 1999 | 52.344845002841 | 1998 | 54.882125228083 | 1997 | 54.897936011425 | 1996 | 55.826676775509 | 1995 | 53.323977884646 | 1994 | 53.366710793415 | 1993 | 54.992053077253 | 1992 | 57.275382713878 | 1991 | 57.695060494468 | 1990 | 57.745322192412 | 1989 | 57.831339469422 | 1988 | 56.489264716117 | 1987 | 56.291194872234 | 1986 | 58.589639781121 | 1985 | 57.368840733831 | 1984 | 61.196365616643 | 1983 | 61.725621627768 | 1982 | 59.502451962039 | 1981 | 61.136482677235 | 1980 | 64.915293149985 | 1979 | 67.379199696521 | 1978 | 71.727712542065 | 1977 | 70.243707677806 | 1976 | 74.691043505576 | 1975 | 70.314071357802 | 1974 | 74.906677337024 | 1973 | 77.364476688624 | 1972 | 80.527885664297 | 1971 | 82.276584622727 | 1970 | 78.737922794352 | 1969 | 80.643386146173 | 1968 | 78.396371194181 | 1967 | 76.256877339776 | 1966 | 76.553945703404 | 1965 | 77.800970987228 | 1964 | 78.342174963064 | 1963 | 78.189485842099 | 1962 | 74.779583799324 | 1961 | 72.205927797462 | 1960 | 71.668300949396 |
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