Year | Value | 2015 | 44.110165965244 | 2014 | 43.485271852002 | 2013 | 46.352875017262 | 2012 | 46.799231066582 | 2011 | 46.060214626134 | 2010 | 48.163465923748 | 2009 | 49.245310930147 | 2008 | 48.518091788808 | 2007 | 49.039075402134 | 2006 | 48.898123336388 | 2005 | 49.381845014349 | 2004 | 49.24383011653 | 2003 | 48.946589363307 | 2002 | 48.658454854998 | 2001 | 49.328587834905 | 2000 | 48.132819614552 | 1999 | 49.034731871795 | 1998 | 49.807765229927 | 1997 | 46.981813358326 | 1996 | 47.383438445199 | 1995 | 46.064588631991 | 1994 | 45.614385809545 | 1993 | 46.56741698473 | 1992 | 48.355333675121 | 1991 | 49.949102912783 | 1990 | 50.058987288194 | 1989 | 50.295223072849 | 1988 | 50.548870842996 | 1987 | 51.092654999 | 1986 | 51.761775203293 | 1985 | 54.21546440146 | 1984 | 56.21885146038 | 1983 | 61.074997249941 | 1982 | 65.226880353429 | 1981 | 65.847106009888 | 1980 | 72.571277205778 | 1979 | 75.078252379209 | 1978 | 75.192995749933 | 1977 | 74.2480131112 | 1976 | 76.656127892761 | 1975 | 73.588113078401 | 1974 | 75.734891339276 | 1973 | 75.477880205964 | 1972 | 72.011607671167 | 1971 | 69.976819908424 | 1970 | 67.335211247253 | 1969 | 68.352673278321 | 1968 | 65.930569207282 | 1967 | 61.145792371323 | 1966 | 57.043551811018 | 1965 | 56.24364949162 | 1964 | 55.38959715257 | 1963 | 55.827843460326 | 1962 | 49.888092935072 | 1961 | 46.520761747828 | 1960 | 42.823201864372 |
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