| Year | Value | | 2021 | 7.4280982874017 | | 2020 | 7.4280982874017 | | 2019 | 7.4280982874017 | | 2018 | 7.4280982874017 | | 2017 | 7.4280982874017 | | 2016 | 7.4280982874017 | | 2015 | 7.4280982874017 | | 2014 | 7.4280982874017 | | 2013 | 7.4280982874017 | | 2012 | 7.4280982874017 | | 2011 | 7.4280982874017 | | 2010 | 7.4280982874017 | | 2009 | 7.4280982874017 | | 2008 | 7.4280982874017 | | 2007 | 7.4231243138553 | | 2006 | 7.4231243138553 | | 2005 | 7.4341066295351 | | 2004 | 7.4564608396317 | | 2003 | 7.4817868039641 | | 2002 | 7.5371132547949 | | 2001 | 7.5614574455875 | | 2000 | 7.5924191793834 | | 1999 | 7.6257695177902 | | 1998 | 7.6997552086831 | | 1997 | 7.7824484923971 | | 1996 | 7.6947312119458 | | 1995 | 7.7846526945888 | | 1994 | 7.8395343967797 | | 1993 | 7.9053202149616 | | 1992 | 8.0542039481511 |
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