Year | Value | 2021 | 26.220429747504 | 2020 | 25.489253816514 | 2019 | 24.022905416906 | 2018 | 23.059665296584 | 2017 | 22.543396382376 | 2016 | 21.154966110267 | 2015 | 20.142483573341 | 2014 | 18.950453908622 | 2013 | 16.288499409612 | 2012 | 15.845531418818 | 2011 | 14.382645163549 | 2010 | 16.282594131945 | 2009 | 14.983634066867 | 2008 | 14.907729851918 | 2007 | 15.15431762095 | 2006 | 13.400378831197 | 2005 | 15.318463685687 | 2004 | 13.564609663577 | 2003 | 14.528749152923 | 2002 | 13.032173271388 | 2001 | 14.670522012263 | 2000 | 11.277395039459 | 1999 | 11.540253068304 | 1998 | 11.138231558199 | 1997 | 10.761934567763 | 1996 | 7.9803454666696 | 1995 | 8.4912589193384 | 1994 | 5.8159364648293 | 1993 | 1.4922602773619 | 1992 | 3.7482174688618 | 1991 | 3.0169264338901 | 1990 | 2.5716747678637 | 1989 | 2.7069232086004 | 1988 | 2.646399689696 | 1987 | 5.9432141682649 | 1986 | 2.6309686283972 | 1985 | 5.0800173780008 | 1984 | 4.9588857893232 | 1983 | 5.2128819687954 | 1982 | 7.9814789504911 | 1981 | 7.4520381605608 | 1980 | 3.4847030327479 | 1979 | 9.2232717035286 | 1978 | 9.8496162349525 | 1977 | 15.36490864737 | 1976 | 15.0064355892 | 1975 | 17.320978130539 | 1974 | 21.028242127302 |
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