Year | Value | 2014 | 52.996436288788 | 2013 | 51.536591238843 | 2012 | 51.610748509672 | 2011 | 52.223267189475 | 2010 | 51.183618255341 | 2009 | 50.713652501166 | 2008 | 55.324652653114 | 2007 | 54.805767266157 | 2006 | 50.467910103368 | 2005 | 54.976855090359 | 2004 | 57.305670730219 | 2003 | 55.513808574605 | 2002 | 54.616161384412 | 2001 | 53.633756392939 | 2000 | 49.065786772568 | 1999 | 49.486754746035 | 1998 | 42.982572998929 | 1997 | 38.54028404191 | 1996 | 40.129266760646 | 1995 | 41.181690573756 | 1994 | 37.132956699112 | 1993 | 33.395709197157 | 1992 | 32.296450038826 | 1991 | 29.103123676007 | 1990 | 28.809388231092 | 1989 | 30.940900378965 | 1988 | 29.503122157642 | 1987 | 27.877927883609 | 1986 | 28.030911759578 | 1985 | 26.648927265959 | 1984 | 30.415266584136 | 1983 | 29.625227782903 | 1982 | 32.05324298882 | 1981 | 28.309837873531 | 1980 | 29.718118451624 | 1979 | 30.690387555156 | 1978 | 30.384451703435 | 1977 | 30.96520723463 | 1976 | 29.107457208135 | 1975 | 27.783571699456 | 1974 | 27.252582666003 | 1973 | 28.215382863402 | 1972 | 26.87795699341 | 1971 | 27.135493902702 |
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