| Year | Value | | 2021 | 11.228212403729 | | 2020 | 11.1876773409 | | 2019 | 11.147142278071 | | 2018 | 11.106607215241 | | 2017 | 11.066072152412 | | 2016 | 11.025537089582 | | 2015 | 10.944466963924 | | 2014 | 10.903931901094 | | 2013 | 10.863396838265 | | 2012 | 10.822861775436 | | 2011 | 10.782326712606 | | 2010 | 10.741791649777 | | 2009 | 10.830968788002 | | 2008 | 10.920145926226 | | 2007 | 11.009323064451 | | 2006 | 11.098500202675 | | 2005 | 11.1876773409 | | 2004 | 11.276854479124 | | 2003 | 11.366031617349 | | 2002 | 11.455208755574 | | 2001 | 11.544385893798 | | 2000 | 11.633563032023 | | 1999 | 11.755168220511 | | 1998 | 11.876773408999 | | 1997 | 11.998378597487 | | 1996 | 12.119983785975 | | 1995 | 12.241588974463 | | 1994 | 12.363194162951 | | 1993 | 12.484799351439 | | 1992 | 12.606404539927 | | 1991 | 12.728009728415 | | 1990 | 12.849614916903 |
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