Year | Value | 2021 | 24.323295583277 | 2020 | 24.345620982223 | 2019 | 23.38108056013 | 2018 | 22.734497054626 | 2017 | 22.779370887129 | 2016 | 22.646575453642 | 2015 | 22.321941850006 | 2014 | 22.751405054816 | 2013 | 23.086183458565 | 2012 | 24.070229069587 | 2011 | 22.724352254513 | 2010 | 23.813227466708 | 2009 | 23.606949864398 | 2008 | 25.355237083979 | 2007 | 24.249453871594 | 2006 | 24.942681879358 | 2005 | 26.308848294659 | 2004 | 26.981786702196 | 2003 | 26.914154701438 | 2002 | 28.023319513861 | 2001 | 28.199162715831 | 2000 | 28.672586721133 | 1999 | 29.05375539764 | 1998 | 28.319336302744 | 1997 | 28.060929584169 | 1996 | 28.329536567951 | 1995 | 28.162932236238 | 1994 | 28.319336302744 | 1993 | 29.070755839652 | 1992 | 29.750773520112 | 1991 | 30.260786780456 | 1990 | 30.641596681514 | 1989 | 30.57699500187 | 1988 | 30.45799190779 | 1987 | 30.821801366836 | 1986 | 30.893203223284 | 1985 | 30.770800040801 | 1984 | 30.930604195709 | 1983 | 31.03600693618 | 1982 | 32.158036108939 | 1981 | 32.185236816157 | 1980 | 32.243038318996 | 1979 | 32.21923770018 | 1978 | 32.134235490123 | 1977 | 31.821427357111 | 1976 | 31.838427799123 | 1975 | 31.722824793445 | 1974 | 31.685423821019 | 1973 | 31.580021080548 | 1972 | 31.937030362789 | 1971 | 32.338240794261 | 1970 | 40.746659413145 | 1969 | 41.552480364489 | 1968 | 41.977491414777 | 1967 | 42.123695216076 | 1966 | 42.310700078202 | 1965 | 42.582707150386 | 1964 | 42.834313692156 | 1963 | 43.092720410731 | 1962 | 43.504131107409 | 1961 | 43.731937030363 |
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