Year | Value | 2015 | 75.207880041183 | 2014 | 74.208111364487 | 2013 | 73.065355419762 | 2012 | 74.017122797971 | 2011 | 71.607576530156 | 2010 | 69.624766595772 | 2009 | 69.035881178924 | 2008 | 70.642006361231 | 2007 | 72.725498826821 | 2006 | 71.712938892441 | 2005 | 71.582265866605 | 2004 | 70.132589402949 | 2003 | 69.71013236801 | 2002 | 67.510477543609 | 2001 | 65.239431657126 | 2000 | 65.958182920194 | 1999 | 60.980388293891 | 1998 | 59.482224414235 | 1997 | 60.290257883221 | 1996 | 59.472360606479 | 1995 | 56.987708473976 | 1994 | 53.210118799541 | 1993 | 53.991633471976 | 1992 | 50.85865159555 | 1991 | 50.684564421066 | 1990 | 51.031722650073 | 1989 | 47.789819564767 | 1988 | 47.562252862303 | 1987 | 46.722609481971 | 1986 | 44.488841634929 | 1985 | 44.406400761977 | 1984 | 45.43182799659 | 1983 | 45.950506070077 | 1982 | 43.728477050124 | 1981 | 43.036899744754 | 1980 | 45.508027435238 | 1979 | 42.423058288897 | 1978 | 44.611835019613 | 1977 | 46.934194527419 | 1976 | 42.953571789188 | 1975 | 39.220719353863 | 1974 | 36.966020627052 | 1973 | 36.255473186902 | 1972 | 31.504440262683 | 1971 | 29.342848616916 | 1970 | 23.184991572491 | 1969 | 19.435914726701 | 1968 | 18.088274208953 | 1967 | 16.256700210398 | 1966 | 19.350595763956 | 1965 | 18.820090522769 | 1964 | 19.243570633854 | 1963 | 18.026198345036 | 1962 | 17.941880543195 | 1961 | 12.586700771082 | 1960 | 12.335653942187 |
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