Year | Value | 2014 | 32.844209577216 | 2013 | 27.819923906996 | 2012 | 25.593919547037 | 2011 | 25.627549259031 | 2010 | 26.373225054236 | 2009 | 31.026437755333 | 2008 | 30.807818169381 | 2007 | 33.439211771915 | 2006 | 31.938629813552 | 2005 | 30.772145019359 | 2004 | 28.10311280912 | 2003 | 23.901468849994 | 2002 | 25.037445777107 | 2001 | 26.748064769767 | 2000 | 25.142641499572 | 1999 | 21.150835252504 | 1998 | 19.530066826598 | 1997 | 19.248723895966 | 1996 | 22.929589096005 | 1995 | 27.755088308492 | 1994 | 28.194388968595 | 1993 | 24.382056004049 | 1992 | 24.894466170751 | 1991 | 24.447839708272 | 1990 | 23.334874135226 | 1989 | 21.600155536848 | 1988 | 21.82379604083 | 1987 | 20.267313221828 | 1986 | 16.451599624154 | 1985 | 26.154913288665 | 1984 | 23.810366683971 | 1983 | 17.385905326441 | 1982 | 20.479719712837 | 1981 | 27.652285750227 | 1980 | 31.886792303573 | 1979 | 32.410349512321 | 1978 | 31.266978052613 | 1977 | 30.031107787584 | 1976 | 26.940833252194 | 1975 | 26.637394441879 | 1974 | 30.702214598536 | 1973 | 30.700268092146 | 1972 | 29.68360640681 | 1971 | 29.28304183088 |
|