Year | Value | 2019 | 49.351435875756 | 2018 | 49.322186798679 | 2017 | 49.28496070421 | 2016 | 49.247861661544 | 2015 | 49.217306641525 | 2014 | 49.195451330352 | 2013 | 49.181102032001 | 2012 | 49.173580233558 | 2011 | 49.170916364899 | 2010 | 49.171471143166 | 2009 | 49.17566263346 | 2008 | 49.184049523725 | 2007 | 49.19500851472 | 2006 | 49.206326605413 | 2005 | 49.216348486272 | 2004 | 49.22420715546 | 2003 | 49.23013526435 | 2002 | 49.23499459831 | 2001 | 49.240303069017 | 2000 | 49.247235097121 | 1999 | 49.255938493234 | 1998 | 49.266026481638 | 1997 | 49.277533666737 | 1996 | 49.290385831627 | 1995 | 49.304473977931 | 1994 | 49.320147871744 | 1993 | 49.337373756059 | 1992 | 49.35513579037 | 1991 | 49.371964326791 | 1990 | 49.386861607887 | 1989 | 49.398855260196 | 1988 | 49.408409735749 | 1987 | 49.417777719505 | 1986 | 49.430424356197 | 1985 | 49.44888387511 | 1984 | 49.474514341496 | 1983 | 49.50642261979 | 1982 | 49.541930217636 | 1981 | 49.576745442287 | 1980 | 49.607353761277 | 1979 | 49.632615383485 | 1978 | 49.652950620841 | 1977 | 49.668217773106 | 1976 | 49.678830778968 |
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