Year | Value | 2021 | 72.72 | 2020 | 73.66 | 2019 | 73.99 | 2018 | 74.13 | 2017 | 74.74 | 2016 | 74.55 | 2015 | 73.77 | 2014 | 74.06 | 2013 | 73.95 | 2012 | 72.86 | 2011 | 72.35 | 2010 | 72.73 | 2009 | 72.71 | 2008 | 72.32 | 2007 | 71.72 | 2006 | 71.28 | 2005 | 71.47 | 2004 | 71.42 | 2003 | 70.44 | 2002 | 69.55 | 2001 | 69.26 | 2000 | 69.01 | 1999 | 69.27 | 1998 | 69.01 | 1997 | 68.61 | 1996 | 68.4 | 1995 | 67.99 | 1994 | 68.59 | 1993 | 68.51 | 1992 | 68.51 | 1991 | 68.53 | 1990 | 68.92 | 1989 | 68.76 | 1988 | 68.68 | 1987 | 68.47 | 1986 | 67.66 | 1985 | 67.25 | 1984 | 66.55 | 1983 | 66.24 | 1982 | 66.44 | 1981 | 66.86 | 1980 | 67.24 | 1979 | 67.74 | 1978 | 67 |
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